MEMS device with micromachined thermistor

ABSTRACT

A micromachined apparatus includes micromachined thermistor having first and second ends physically and thermally coupled to a substrate via first and second anchor structures to enable a temperature-dependent resistance of the micromachined thermistor to vary according to a time-varying temperature of the substrate. The micromachined thermistor has a length, from the first end to the second end, greater than a linear distance between the first and second anchor structures.

CROSS-REFERENCE TO RELATED APPLICATIONS

This non-provisional application is a divisional of U.S. patentapplication Ser. No. 13/607,597, filed Sep. 7, 2012 and entitled“Micromachined Thermistor and Temperature Measurement Circuitry (nowU.S. Pat. No. 9,022,644), and Method of Manufacturing and OperatingSame,” which claims priority to U.S. Provisional Application No.61/533,148, entitled “Micromachined Thermistor and TemperatureMeasurement Circuitry, and Method of Manufacturing and Operating Same,”filed Sep. 9, 2011. Each of the above-identified patent applications ishereby incorporated by reference.

INTRODUCTION

The present inventions are directed to, among other things, amicromachined thermistor (and the method of manufacturing such athermistor) having predetermined and/or high correlation of resistanceto ambient temperature and, preferably, limited, minimized and/orreduced stress-resistance dependence and/or improved long-termstability. In one embodiment, the thermistor includes one or moremicromachined thermistor structures which are fabricated from atemperature-sensitive crystalline material (for example, doped orundoped semiconductor material(s) such as, for example, monocrystalline,polycrystalline and/or amorphous silicon, germanium, silicon/germanium,silicon carbide (SiC), and gallium arsenide) using any micromachiningprocessing or fabrication techniques now known or later developed. Inaddition thereto, or in lieu thereof, the thermistor may include one ormore micromachined thermistor structure which are fabricated from ametal material (for example, platinum, aluminum, molybdenum, titaniumand/or copper (or alloys thereof)).

For example, in one embodiment, the micromachined thermistor structuremay be fabricated from a doped monocrystalline or polycrystallinesilicon (for example, doped with a p-type impurity (such as, forexample, boron, aluminum, gallium, or other element in group 13 of theperiodic table as well as compounds) or an n-type impurity (such as, forexample, phosphorus and/or arsenic)) using well-known deposition,lithographic and/or doping techniques. In another embodiment, themicromachined thermistor structure may be fabricated from platinum,molybdenum, titanium and/or copper (or alloys thereof). Indeed, inanother embodiment, the thermistor includes a plurality of thermistorstructures including at least one micromachined thermistor structurefabricated from a doped monocrystalline or polycrystalline semiconductormaterial and at least one micromachined thermistor structure fabricatedfrom a metal material.

Where the micromachined thermistor structure includes or is fabricatedfrom a impurity doped semiconductor material, in one embodiment, theimpurity dopant type and/or doping levels (both of which may depend on agiven base or substrate material of the structure) may be selected toprovide a predetermined, increased, linearized enhanced and/or maximumsensitivity of the temperature dependent characteristic of the structure(for example, resistance) relative to undoped or intrinsic semiconductormaterial. In another embodiment, the micromachined thermistor structureis doped with a dopant type and/or at doping levels that provide apredetermined increase in sensitivity of the temperature dependentcharacteristic of the structure (for example, resistance) in relation toa predetermined and/or minimum sensitivity to doping variations (whichmay depend on manufacturing controllability and/or tolerances of thedoping operation) and/or linearity of the change of the temperaturedependent characteristic of the structure (for example, resistance) overtemperature (for example, an operating or predetermined temperaturerange). For example, in one embodiment, the impurity doping levelsprovide a predetermined enhancement of the sensitivity of thetemperature dependent characteristic of the structure (for example,resistance) but such sensitivity over a range of doping levels (forexample, the manufacturing controllability and/or tolerances of thedoping operation) is within a predetermined sensitivity range. In thisway, although the dopant and doping levels may not provide a maximumsensitivity to the temperature dependent characteristic of themicromachined thermistor structure, such dopant and/or levels provide anincrease in the temperature dependent characteristic, relative to anundoped base material of the structure, and a sensitivity of thetemperature dependent characteristic (for example, resistance) overmanufacturing variations or tolerances in doping operations orconcentrations is within a predetermined range or limits.

Notably, in one embodiment, the doping processes (which may employmultiple masking processes) of the micromachined thermistor structuremay include a plurality of impurity dopant types and/or a plurality ofdoping levels, which, in sum, provide a net doping concentration. In oneembodiment, the doping processes may include (i) a first impurity dopanttype at first doping level and (ii) a second impurity dopant type (whichis the same impurity type as the first impurity dopant type) at a seconddoping level. In another embodiment, the doping processes may includecounter-doping which includes (i) a first impurity dopant type at firstdoping level and (ii) a second impurity dopant type (which is oppositethe first impurity dopant type) at a second doping level. In the contextof counter-doping, the dominant impurity type and the net dopingconcentration of the micromachined thermistor structure depend on, amongother things, the impurity dopant types and the doping levels of suchimpurities. Indeed, in another embodiment, the doping processes of thethermistor (which may employ multiple masking processes) may provide afirst region of the thermistor (for example, the electrical contacts)having first impurity dopant type(s) and/or first impurity dopinglevel(s), and a second region of the thermistor (for example, themicromachined thermistor structure) having second impurity dopanttype(s) and/or second impurity doping level(s).

The thermistor of the present inventions may be a discrete device orintegrated on a substrate or die with one or more other structures (forexample, one or more mechanical structures of a micro- ornano-electromechanical device (MEMS or NEMS device, respectively,hereinafter collectively “MEMS device”)). In addition thereto, or inlieu thereof, the thermistor may be integrated with circuitry as anintegrated circuit type device. In this regard, the thermistor of thepresent inventions (which may have one or more micromachined thermistorstructures) may be integrated on a die including integrated circuitryand/or one or more MEMS devices having one or more other structures (forexample, one or more mechanical structures of a micro- ornano-electromechanical device).

In one embodiment, the micromachined thermistor structure may bepartially, substantially or entirely released (vertically and/orhorizontally), suspended, and/or “free-standing” relative to thesubstrate. For example, in one embodiment, the micromachined thermistorstructure may be vertically and/or horizontally released and/orsuspended (for example, in a cantilever-like manner) above the substrateto limit and/or reduce changes in the temperature dependentcharacteristics (for example, resistance) of the structure due tostresses in the substrate (for example, internal or external stressesintroduced during operation). In these embodiments, the temperaturedependent characteristics (for example, resistance) of the micromachinedthermistor structure, which is partially, substantially or entirelyreleased (vertically and/or horizontally), suspended, and/or“free-standing” relative to the substrate, are substantially independentof internally or externally induced stresses in the substrate and, assuch, provide a more accurate and/or a more reliable representation ofthe ambient temperature regardless of the non-temperaturerelated/dependent ambient operating conditions of the thermistor (forexample, substrate stress or forces (internal or external) appliedthereto).

In one embodiment, the micromachined thermistor structure of thethermistor is unsealed or not encapsulated, but is exposed to theambient atmosphere. In another embodiment, the micromachined thermistorstructure is sealed or encapsulated in a cavity. Here, the micromachinedthermistor structure may be sealed or encapsulated in a cavity using anytechnique now known or later developed. (See, for example, MEMSfabrication, encapsulation and packaging process as described andillustrated in U.S. Pat. Nos. 6,146,917; 6,307,815; 6,352,935;6,477,901; 6,507,082; 6,936,491; 7,075,160; and/or 7,514,283). Moreover,in one embodiment, the micromachined thermistor structure of thethermistor is sealed or encapsulated in a cavity having a predeterminedenvironment and fluid (for example, a cavity having a vacuum environmentor having a predetermined pressure and/or fluid (for example, hydrogenand/or an inert gas such as helium). (See, for example, U.S. Pat. No.7,514,283). Indeed, in one embodiment, a fluid (for example, gas orliquid such as, for example, helium, argon, nitrogen, an oil, a siliconliquid and a silicon gel) may be disposed in the cavity and/or aroundthe thermistor to, for example, enhance thermal conductivity/contactwith other portions of the die, other structures disposed or fabricatedin the die (for example, a MEMS device such as a MEMS resonator,accelerometer, gyroscope, pressure sensor and/or combinations thereof)and/or with structures disposed or fabricated in a related/associateddie (for example, a MEMS device disposed or fabricated in therelated/associated die).

The micromachined thermistor structure of the thermistor may include oneor more anchors which secure, attach and/or physically couple thethermistor structure to the substrate of the discrete, integrated and/orintegrated circuit device. In addition thereto, or in lieu thereof, themicromachined thermistor structure of the thermistor may include one ormore anchors which secure, attach and/or physically couple thethermistor structure to the encapsulation structure of the discrete,integrated and/or integrated circuit device. Notably, the one or moreanchors may be displaced (for example, laterally) relative to the signalflow (for example, current flow) through or in the micromachinedthermistor structure. In this way, the impact of internal or externalstress introduced into the micromachined thermistor structure via theanchors may be limited, minimized and/or reduced in relation to thetemperature dependent output signal.

The micromachined thermistor structure of the thermistor may include astem-loop or hairpin loop shape (hereinafter collectively,“loop-shape”). Under these circumstances, the anchors are located inclose proximity (for example, juxtaposed) such that the anchors secure,attach and/or physically couple the thermistor structure to thesubstrate and/or encapsulation material/structure of the sensor or theintegrated device. In this way, displacement of or impact on themicromachined thermistor structure (or portions thereof) due to internalor external stress may be limited, minimized and/or reduced therebylimiting and/or reducing the impact on the thermistor's temperaturedependent output signal.

Moreover, a loop-shape (wherein the anchors of the micromachinedthermistor structure are located in close proximity) may increase therigidity, restoring force and/or resonant frequency of the micromachinedthermistor structure of the thermistor in response to external forces orvibration applied to the substrate (particularly in those embodimentswhere the micromachined thermistor structure is partially, substantiallyor entirely released (vertically and/or horizontally), suspended, or“free-standing” relative to the substrate). In addition to limitingand/or reducing the impact of such external forces on the temperaturedependent characteristics (for example, resistance) of the micromachinedthermistor structure (which will improve the accuracy and/or reliabilityof the temperature dependent output signal of the structure), therigidity, restoring force and/or resonant frequency of the micromachinedthermistor structure of the thermistor will reduce or minimize stictionconcerns—wherein the micromachined thermistor structure comes inphysical contact with nearby structure, the substrate and/or the cover(in those embodiments where the micromachined thermistor structure ofthe thermistor is encapsulated or a protective cover is disposed overthe structure).

The micromachined thermistor structure of the thermistor may alsoinclude (in whole or in part) a serpentine or undulating shape. Forexample, where the micromachined thermistor structure includes aloop-shape, one or more of the legs or portions of the loop-shape of themicromachined thermistor structure may include a serpentine orundulating shape or structure to, among other things, increase theamplitude of the output signal corresponding to the temperaturedependent characteristics of the micromachined thermistor structure,increase resistance of the overall structure and/or limit and/or reducethe impact on the micromachined thermistor structure (or portionsthereof) of internal or external stress. Indeed, in one embodiment, themicromachined thermistor structure includes one or more major portionsof the loop-shape of the micromachined thermistor structure which aresymmetrical or substantially symmetrical (for example, in relation to anaxis of the structure), such major portions may include symmetrical orsubstantially symmetrical serpentine or undulating shapes.

In addition, in one embodiment, the thermistor includes two or moreelectrical contacts to input and/or output signals from the thermistor.The electrical contacts facilitate measurement of a temperaturedependent characteristics of the micromachined thermistor structure(and/or change therein) of the thermistor. In one embodiment, thethermistor includes two electrical contacts to facilitate a 2-pointsensing configuration/architecture where measurement circuitry samples,detects and/or measures the temperature dependent characteristics(and/or changes therein) of the micromachined thermistor structure (forexample, resistance or change in resistance of the micromachinedthermistor structure). In another embodiment, the thermistor includesfour electrical contacts to facilitate implementation of 2-point,3-point or 4-point sensing configurations/architectures wherein a4-point sensing configuration/architecture may facilitate more accuratemeasurement of the temperature dependent characteristics (for example,resistance), and/or change therein, of the thermistor with minimal,reduced, little or no contribution to the overall or measured resistancedue to, for example, (i) the electrical contacts or signal path to themeasurement circuitry and/or (ii) non-idealities of the measurementcircuitry.

Notably, in one embodiment, one or more of the electrical contacts ofthe thermistor and/or the micromachined thermistor structure arephysically integrated or disposed in one or more of the anchors of thethermistor. Indeed, where the anchors are laterally displaced relativeto the signal flow (for example, current flow) through or in themicromachined thermistor structure, it may be advantageous to physicallyintegrate or dispose the electrical contacts in the anchors of thethermistor to limit and/or reduce the impact of internal or externalstress introduced into the micromachined thermistor structure via theanchors and thereby limit and/or reduced the impact of such forces onthe temperature dependent output signal. In this way, the thermistorprovides a more accurate and/or a more reliable representation of theambient temperature regardless of the non-temperature related/dependentambient operating conditions of the thermistor (for example, substratestress or forces (internal or external) applied thereto).

In those embodiments where the micromachined thermistor structureprovides information which is representative of another structure (forexample, a one or more mechanical structures of a MEMS device), athermal coupler may be employed to enhance the thermal coupling of thestructure with the micromachined thermistor structure. In this way, thethermistor provides a more accurate and/or a more reliablerepresentation of the temperature of the other structure even where thestructures are disposed in a cavity having a vacuum environment. Indeed,in one embodiment, the micromachined thermistor structure may share orphysically contact the other structure (for example, the micromachinedthermistor structure may share an anchor with one or more mechanicalstructures of a MEMS device). Such an embodiment enhances the thermalexchange between the thermistor and the other structure and, where thestructures are disposed in a cavity having a vacuum environment, such anexchange may dramatically enhance the accuracy and reliability of therepresentation of temperature of the other structure by the thermistor.

As intimated above, the thermistor may electrically couple tomeasurement circuitry. In one embodiment, the measurement circuitryincludes resistance, voltage and/or current sensors (for example, an ohmmeter, a voltmeter and/or a current meter). Any resistance, voltageand/or current sensors, whether now known or later developed, may beemployed in conjunction with the thermistors of the present inventions.Indeed, the measurement circuitry may be configured in a 2-pointconfiguration/architecture (for example, ohm meter type circuitrycoupled to electrical connection or contact points of the thermistor).In another embodiment, the measurement circuitry may be configured in3-point or 4-point configuration/architecture (for example, currentmeter and voltmeter type circuitry coupled to electrical connection orcontact points of the thermistor). The circuitry may include a bridgenetwork, configuration or architecture (for example, a Wheatstonebridge). Such bridge may be 2 or 4 element, and may be AC or DC excited,and may include one or more active or passive elements includingresistors, capacitors, inductors and/or transistors/diodes.

Notably, the measurement circuitry may be partially or wholly (i)integrated on the same substrate or die as the thermistor or (ii)disposed on a separate or different die.

Importantly, in one aspect, the present inventions are directed tomeasurement circuitry and methods of operating such circuitry. In oneembodiment of this aspect, the measurement circuitry minimizes theimpact of non-idealities of the measurement system and/or configurationto measure the temperature dependent characteristics of themicromachined thermistor structure and/or change therein (for example,resistance introduced via the measurement circuitry) by measuring aparameter (for example, capacitance) that is a measure of but differentfrom the temperature dependent characteristics of the micromachinedthermistor structure (for example, resistance).

Moreover, such inventions provide a low noise temperature sensing withhigh accuracy, low power, and/or low area using a thermistor element asthe micromachined temperature sensitive device (for example, one or moreof the thermistors of the present inventions wherein the resistance ofthe micromachined thermistor structure depends on or changes withtemperature). For example, in one embodiment, the measurement circuitryincludes a switched capacitor network that creates a low noise adaptablereference resistor for comparison purposes, a frequency divider that iscontrolled by a digital Sigma-Delta modulator (also known as aDelta-Sigma modulator—which hereinafter identified as a “Sigma-Delta”modulator) to achieve an accurately controlled switching frequency forthe switched capacitor network, a chopping method to mitigate the effectof 1/f noise and circuit offsets, a pseudo-differential VCO-basedanalog-to-digital converter structure to efficiently convert the analogerror between the MEMS-based resistance value and the effectiveresistance of the switched capacitor network into a digital code, and anoverall feedback loop that changes a Sigma-Delta modulator input inresponse to that error. In this way, the measurement circuitry minimizesthe impact of non-idealities of the measurement system and/orconfiguration to measure the temperature dependent characteristics ofthe micromachined thermistor structure and/or change therein (forexample, resistance introduced via the measurement circuitry) bymeasuring a parameter (for example, capacitance) that is a measure ofbut different from the temperature dependent characteristics of themicromachined thermistor structure (for example, resistance).

The measurement circuitry may electrically couple to data processingcircuitry. Here the data processing circuitry, using the output signalof the measurement circuitry (which may be a measure of the temperaturedependent resistance and/or change therein), may determine and/orgenerate data which is indicative or representative of a temperatureand/or change therein. The data processing circuitry may be partially orwholly (i) integrated on the same substrate(s)/die(dice) as thethermistor and/or measurement circuitry or (ii) disposed on a separateor different substrate/die. Notably, the data processing circuitry maybe one or more processors, one or more state machines, one or moreprocessors implementing software, one or more gate arrays, programmablegate arrays and/or field programmable gate arrays (whether integrated orotherwise). Indeed, the processing circuitry may be any circuitry nowknown or later developed which determines, calculates and/or generatedata which is indicative or representative of a temperature (and/orchange therein) based on or using the output signal of the measurementcircuitry.

BRIEF DESCRIPTION OF THE DRAWINGS

In the course of the detailed description to follow, reference will bemade to the attached drawings. These drawings show different aspects ofthe present inventions and, where appropriate, reference numeralsillustrating like structures, components, materials and/or devices indifferent figures are labeled similarly. It is understood that variouscombinations of the structures, components, and/or devices, other thanthose specifically shown, are contemplated and are within the scope ofthe present inventions.

Moreover, there are many inventions described and illustrated herein.The present inventions are neither limited to any single aspect norembodiment thereof, nor to any combinations and/or permutations of suchaspects and/or embodiments. Moreover, each of the aspects of the presentinventions, and/or embodiments thereof, may be employed alone or incombination with one or more of the other aspects of the presentinventions and/or embodiments thereof. For the sake of brevity, certainpermutations and combinations are not discussed and/or illustratedseparately herein.

FIGS. 1A-1C illustrate block diagram representations of a thermistor,implemented in various system configurations, according to certainaspects of certain embodiments of the present inventions, wherein FIG.1A illustrates a thermistor including a micromachined thermistorstructure disposed on or in a substrate, FIG. 1B illustrates athermistor (according to any of the embodiments disclosed herein)electrically coupled to measurement circuitry, and FIG. 1C illustrates athermistor (according to any of the embodiments disclosed herein)electrically coupled to measurement circuitry, which is coupled to dataprocessing circuitry (notably, the data processing circuitry, in certainembodiments, employs the data which is representative of the ambienttemperature, as measured by the measurement circuitry, to calculate,generate and/or determine data which is indicative or representative oftemperature);

FIGS. 1D-1F illustrate block diagram representations of the systemarchitecture of FIG. 1C (which includes a thermistor) in conjunctionwith clock generation circuitry (for example, one or more integer and/orfractional phase locked loops (PLLs), delay locked loops (DLLs),digital/frequency synthesizer (for example, a direct digital synthesizer(“DDS”), frequency synthesizer, fractional synthesizer and/ornumerically controlled oscillator) and/or frequency locked loops(FLLs)), wherein in FIGS. 1E and 1F, the system also includes a MEMSdevice (for example, a MEMS resonator, accelerometer, gyroscope,pressure sensor and/or combinations thereof) and the clock generationcircuitry may employ the output signal of the MEMS device as a referencesignal to generate a clock output signal having a predetermined,substantially stable frequency, and the data processing circuitryemploys the data from the thermistor (which provides information of theoperating temperature of the MEMS device) to adjust the operation of theclock generation circuitry (for example, adjust, change one or morevalues or parameters of the PLL or DLL circuitry in accordance with orto accommodate for changes in temperature—see, for example, U.S. Pat.No. 6,995,622);

FIGS. 2A-2C illustrate top views of exemplary thermistors according tocertain aspects and embodiments of the present inventions wherein themicromachined thermistor structure, in one embodiment, may include aloop-shape wherein the anchors are located in close proximity such thatthe anchors secure, attach and/or physically couple the thermistorstructure to the substrate, (FIG. 2A), may include a generally linear orstraight shape such that the anchors are located at distant ends (FIG.2B), or may include a generally curved and/or undulating shape (FIG. 2C)wherein again the anchors are located at distant ends, or, as discussedin connection with other embodiments, combinations thereof; notably, inthese exemplary illustrated embodiments, the electrodes are disposed orintegrated in or on the anchors; moreover, the shapes of themicromachined thermistor structure of these embodiments are merelyexemplary and the inventions hereof are not limited to any particularshape—but may take any shape now known or later developed;

FIGS. 3A-3E illustrate cross-sectional views of the portion of theexemplary thermistor of FIGS. 2A-2C (along dotted line A-A, B-B, C-C,D-D, and E-E respectively), wherein FIG. 3A illustrates across-sectional view of the anchors and electrodes, FIG. 3B illustratesa cross-sectional view of a center section of the micromachinedthermistor structure which is (i) disposed and suspended over (forexample, in a cantilever-like manner) and/or (ii) vertically andhorizontally released from the substrate, FIG. 3C illustrates an endportion of the micromachined thermistor structure which is also (i)disposed and suspended over (for example, in a cantilever-like manner)and/or (ii) vertically and horizontally released from the substrate,FIG. 3D illustrates a cross-sectional view of an end portion of themicromachined thermistor structure wherein the sectional view of FIG. 3Dis perpendicular to the sectional view of FIG. 3C, and FIG. 3Eillustrates a cross-sectional view of the anchor and electrode of theexemplary thermistor of FIGS. 2A and 2B;

FIGS. 4A-4C illustrate cross-sectional views (along dotted line B-B ofFIGS. 2A-2C) at various stages of manufacturing of the exemplarythermistors of FIGS. 2A-2C, wherein FIG. 4A illustrates across-sectional view of substrate prior to formation of themicromachined thermistor structure (wherein in this exemplaryillustration, the starting wafer may be a semiconductor-on-insulatorwafer or a metal-on-insulator-on-substrate type wafer, FIG. 4Billustrates a cross-sectional view of the micromachined thermistorstructure after definition or formation (using, for example, well-knownlithographic and etching techniques), FIG. 4C illustrates themicromachined thermistor structure after removal of the sacrificial orinsulating layer wherein the micromachined thermistor structure is (i)disposed and suspended over (for example, in a cantilever-like manner)and/or (ii) vertically and horizontally released from the substrate, inaccordance with certain aspects and/or embodiments of the presentinventions;

FIG. 5A illustrates a top view of an exemplary thermistor according tocertain aspects and embodiments of the present inventions wherein theexemplary thermistor includes two anchors located in close proximitysuch the anchors secure, attach and/or physically couple the thermistorstructure to the substrate, two electrical contacts disposed orintegrated in or on the anchors, and a micromachined thermistorstructure including (i) a loop-shape and (ii) a serpentine or undulatingshape in a center section or portion of the micromachined thermistorstructure wherein the serpentine or undulating shape, among otherthings, may increase the temperature dependent characteristics of themicromachined thermistor structure, increases resistance of the overallstructure and/or limits and/or reduces the impact on the micromachinedthermistor structure (or portions thereof) of internal or externalstress;

FIG. 5B illustrates a top view of an exemplary thermistor according tocertain aspects and embodiments of the present inventions wherein theexemplary thermistor includes four electrical contacts disposed orintegrated in or on the anchors, which are located in close proximitysuch the anchors secure, attach and/or physically couple the thermistorstructure to the substrate; notably, the shape of micromachinedthermistor structure is substantially similar to that of FIG. 5A;

FIG. 5C illustrates a top view of an exemplary thermistor according tocertain aspects and embodiments of the present inventions wherein theexemplary thermistor includes four electrical contacts—two electricalcontacts are disposed or integrated in or on associated anchors (whichare located in close proximity such the anchors secure, attach and/orphysically couple the thermistor structure to the substrate) and twoelectrical contacts are free-standing above/over the substrate and notdisposed or integrated in or on anchors; notably, the shape ofmicromachined thermistor structure is substantially similar to that ofFIGS. 5A and 5B;

FIG. 5D illustrates a top view of an exemplary thermistor according tocertain aspects and embodiments of the present inventions wherein theexemplary thermistor includes three electrical contacts—two electricalcontacts are disposed or integrated in or on associated anchors (whichare located in close proximity such the anchors secure, attach and/orphysically couple the thermistor structure to the substrate) and oneelectrical contacts are free-standing above/over the substrate and notdisposed or integrated in or on anchors; notably, the shape ofmicromachined thermistor structure is substantially similar to that ofFIGS. 5A and 5B;

FIGS. 6A and 6B illustrate a cross-sectional view, along dotted lineA-A, of the exemplary thermistor illustrated in FIG. 5A, wherein themicromachined thermistor structure is (i) disposed and suspended over(for example, in a cantilever-like manner) and/or (ii) vertically andhorizontally released from the substrate, in accordance with certainaspects and/or embodiments of the present inventions; notably, theexemplary thermistor of FIG. 6B includes a passivation layer (forexample, grown and/or deposited silicon oxide and/or silicon nitridematerials) on the thermistor structure to, among other things, improvethe long term stability of the thermistor (wherein the temperaturedependent characteristics of the thermistor may be more stable over time(for example, less change in resistance over time); notably, apassivation layer may be comprised of a plurality of layers each havingone or more different materials (for example, a silicon nitride layerdisposed on a silicon oxide layer);

FIG. 6C illustrates a cross-sectional view, along dotted line A-A, ofthe exemplary thermistor illustrated in FIG. 5A, wherein the thermistorincludes a material (for example, a compliant like material such as agel, soft plastic or rubber (for example, silicon rubber) like material)that does not communicate appreciable stress to the micromachinedthermistor structure but protects the thermistor structure to, amongother things, improve the long term stability of the thermistor (whereinthe temperature dependent characteristics of the thermistor may be morestable over time (for example, less change in resistance over time);

FIGS. 7A-7C illustrate exemplary measuring techniques and architecturesto determine the temperature dependent characteristics of themicromachined thermistor structure and/or change therein (for example,resistance), wherein, in FIG. 7A, ohm meter type circuitry may becoupled to the thermistor, in a 2-point measurementarchitecture/configuration, to measure a resistance or changes inresistance of the thermistor in response to the ambient temperature ofthe micromachined thermistor structure; in FIG. 7B, current meter andvoltmeter type circuitry may be coupled to the thermistor, in a 4-pointmeasurement architecture/configuration, to measure a resistance orchanges in resistance of the thermistor wherein the resistance of thethermistor is determined by applying/forcing a current, I, across theF+/F− terminals, and sensing a voltage, V, across the S+/S− terminals;and, in FIG. 7C, current meter and voltmeter type circuitry may becoupled to the thermistor, in a 3-point measurementarchitecture/configuration, to measure a resistance or changes inresistance of the thermistor wherein the resistance of the thermistor isdetermined by applying/forcing a current, I, across the F+/F− terminals,and sensing a voltage, V, across the S+/S− terminals; notably, themeasuring circuitry of FIGS. 7B and 7C may measure a parameter (forexample, capacitance) although representative of temperature dependentcharacteristics of the micromachined thermistor structure, is differentfrom the temperature dependent characteristics (for example, resistance)of the micromachined thermistor structure;

FIG. 7D illustrates exemplary measuring technique and architectureemploying a bridge-type circuit to determine the temperature dependentcharacteristics of the micromachined thermistor structure and/or changetherein (for example, resistance), in accordance with certain aspectsand/or embodiments of the present inventions wherein at least oneportion of the bridge corresponds to the temperature dependent parameterof the micromachined thermistor structure;

FIG. 8A illustrates a cross-sectional view, along dotted line A-A, ofthe exemplary thermistor illustrated in FIG. 5A wherein the exemplarythermistor is disposed in a cavity via thin-film encapsulationstructure, in accordance with certain aspects and/or embodiments of thepresent inventions;

FIG. 8B illustrates a cross-sectional view, along dotted line A-A, ofthe exemplary thermistor illustrated in FIG. 5A wherein the exemplarythermistor is sealed, for example, in a TO-8 “can” (or like structure)and/or in a cavity via a wafer or glass substrate bonded to thethermistor die or substrate, in accordance with certain aspects and/orembodiments of the present inventions;

FIGS. 9A-9E illustrate cross-sectional views, along dotted line A-A ofthe exemplary thermistor illustrated in FIG. 5A, at various stages ofmanufacturing, wherein FIG. 9A illustrates a cross-sectional view of themicromachined thermistor structure after formation and prior to releasefrom the substrate, FIG. 9B illustrates a cross-sectional view of themicromachined thermistor structure after providing or depositing asacrificial layer on the micromachined thermistor structure, FIG. 9Cillustrates a cross-sectional view after forming, depositing, growingand/or providing an encapsulation layer on and/or over sacrificial layerand prior to release of the micromachined thermistor structure from thesubstrate (via removal or etching of the sacrificial layer from aroundthe micromachined thermistor structure), and FIG. 9D illustrates across-sectional view after releasing of the micromachined thermistorstructure from the substrate wherein the sacrificial layer is removed oretched from around micromachined thermistor structure therebysubstantially or entirely releasing (vertically and horizontally)micromachined thermistor structure; in one embodiment, the vents areclosed and the cavity sealed after releasing micromachined thermistorstructure, for example, via deposition forming, depositing, growingand/or providing another encapsulation layer (see FIG. 9E); notably, inone embodiment, vents (not illustrated in this series of figures) areformed in encapsulation layer and the sacrificial layer is removed oretched around micromachined thermistor structure using well knownprocessing techniques; in this way, the temperature dependentcharacteristics (for example, resistance) of micromachined thermistorstructure, which is released (vertically and/or horizontally),suspended, and/or “free-standing”, are relatively and/or substantiallyindependent of internally or externally induced stresses in substrateand, as such, provide a more accurate and/or reliable representation ofthe ambient temperature notwithstanding any non-temperaturerelated/dependent ambient operating conditions of thermistor (forexample, substrate stress or forces (internal or external) appliedthereto);

FIGS. 10A and 10B illustrate top views of an exemplary thermistorsaccording to certain aspects and embodiments of the present inventionswherein the micromachined thermistor structure includes (i) a loop-shapeand (ii) a serpentine or undulating shape in a plurality of portions ofthe micromachined thermistor structure wherein the serpentine orundulating shape, among other things, increases the temperaturedependent characteristics of the micromachined thermistor structure,increases resistance of the overall structure and/or limits and/orreduces the impact on the micromachined thermistor structure (orportions thereof) of internal or external stress; notably, exemplarythermistors illustrated in FIG. 10B includes an anchor which is offsetor displaced from signal (for example, current flow I_(signal)) throughor in the micromachined thermistor structure such that the impact ofinternal or external stress introduced into the micromachined thermistorstructure via the offset or displaced anchor may be limited, minimizedand/or reduced in relation to the temperature dependent output signal;

FIG. 10C illustrates a top view of an exemplary thermistor according tocertain aspects and embodiments of the present inventions wherein themicromachined thermistor structure includes the shape and attributes ofFIG. 10B, however, in this exemplary illustrated embodiment, thethermistor includes two electrical contacts to be implemented in a2-point measurement architecture/configuration, wherein, for example,ohm meter type circuitry may measure a resistance or changes inresistance of the thermistor in response to the ambient temperature(see, for example, FIG. 7B);

FIG. 10D illustrates a top view of an exemplary thermistor according tocertain aspects and embodiments of the present inventions wherein themicromachined thermistor structure includes the shape and attributes ofFIGS. 10B and 10C, however, in this exemplary illustrated embodiment,the thermistor includes three electrical contacts to be implemented in a3-point measurement architecture/configuration, wherein, for example,current meter and voltmeter type circuitry may be coupled to thethermistor of FIG. 10D, in a 3-point measurementarchitecture/configuration, to measure a resistance or changes inresistance of the thermistor wherein the resistance of the thermistor isdetermined by applying/forcing a current, I, across the F+/F− terminals,and sensing a voltage, V, across the S+/S− terminals (see, for example,FIG. 7C);

FIGS. 11A-11C illustrate cross-sectional views, along dotted line A-A,of the exemplary thermistor illustrated in FIGS. 10A-10D, in accordancewith certain aspects and/or embodiments of the present inventions,wherein the exemplary thermistor of FIG. 11B is disposed in a cavity viathin-film encapsulation structure, in accordance with certain aspectsand/or embodiments of the present inventions, and the exemplarythermistor of FIG. 11C is sealed, for example, in a TO-8 “can” (or likestructure) and/or in a cavity via a wafer or glass substrate bonded tothe thermistor die or substrate, in accordance with certain aspectsand/or embodiments of the present inventions;

FIGS. 12A and 12B illustrate a top view of an exemplary thermistoraccording to certain aspects and embodiments of the present inventionswherein the micromachined thermistor structure (i) is substantially orentirely released (vertically and/or horizontally), suspended over,and/or “free-standing” relative to the substrate, and is substantiallyindependent of internally or externally induced stresses in thesubstrate, and (ii) includes a serpentine or undulating shape which,among other things, increases the temperature dependent characteristicsof the micromachined thermistor structure, increases resistance of theoverall structure and limits and/or reduces the impact on themicromachined thermistor structure (or portions thereof) of internal orexternal stress;

FIGS. 12C and 12D illustrate a top view of an exemplary thermistoraccording to certain aspects and embodiments of the present inventionswherein the micromachined thermistor structure is substantially orentirely released (vertically and/or horizontally), suspended over,and/or “free-standing” relative to the substrate, and is substantiallyindependent of internally or externally induced stresses in thesubstrate;

FIG. 12E illustrates a top view of an exemplary thermistor according tocertain aspects and embodiments of the present inventions wherein themicromachined thermistor structure includes a beam, having varyingwidths, which is substantially or entirely released (vertically and/orhorizontally), suspended over, and/or “free-standing” relative to thesubstrate, and is substantially independent of internally or externallyinduced stresses in the substrate;

FIGS. 13A and 13B illustrate cross-sectional views, along dotted lineA-A, of the exemplary thermistor illustrated in (i) FIGS. 12A and 12Band (ii) FIGS. 12C and 12D, respectively, in accordance with certainaspects and/or embodiments of the present inventions;

FIGS. 14A and 14B illustrate discrete thermistor devices, in accordancewith aspects and/or embodiments of the present inventions, wherein thethermistor of FIG. 14A includes one micromachined thermistor structureand FIG. 14B includes more than one micromachined thermistor structure(in this exemplary illustrated embodiment, the thermistor includes twomicromachined thermistor structures—although the thermistor may includemore than two micromachined thermistor structures);

FIG. 14C illustrates a thermistor (in accordance with aspects and/orembodiments of the present inventions) fabricated, manufactured orintegrated on a die with a MEMS device, wherein the MEMS device includesone or more MEMS structures and may be, for example, one or moregyroscopes, resonators, pressure sensors, micro-channel and/oraccelerometers;

FIGS. 14D and 14E illustrate a thermistor having a plurality ofmicromachined thermistor structures (in accordance with aspects and/orembodiments of the present inventions) fabricated, manufactured orintegrated on a die with a MEMS device, wherein data from thethermistors may provide, for example, information which isrepresentative of (i) a temperature gradient in/on the die, (ii) hotspots in/on the die, and/or (iii) an average temperature across/inportions of the die, in accordance with certain aspects and/orembodiments of the present inventions; notably, the multiple thermistorsmay be implemented in any of the embodiments described and illustratedherein including any of the embodiments of FIG. 14; moreover, althoughtwo or four thermistor structures are illustrated, three or more thanfour thermistor structures may also be implemented to provide, forexample, additional or more granular temperature dependent data of morethan two or four regions of the die;

FIGS. 14F and 14G illustrate a thermistor (in accordance with aspectsand/or embodiments of the present inventions—which may include one ormore micromachined thermistor structures) fabricated, manufactured orintegrated on a die with integrated circuitry, for example, circuitry ofor associated with measuring the temperature dependent data of thethermistor, in accordance with certain aspects and/or embodiments of thepresent inventions; notably, as mentioned above, although two thermistorstructures are illustrated, more than two thermistor structures may beimplemented to provide additional or more granular temperature dependentdata (for example, data which is reflective (i) a temperature gradientin/on the die, (ii) hot spots in/on the die, and/or (iii) an averagetemperature across/in portions of the die) of more than two regions ofthe die;

FIG. 14H illustrates a thermistor (in accordance with aspects and/orembodiments of the present inventions) having one or more thermistorstructures fabricated, manufactured or integrated on a die with a MEMSdevice and integrated circuitry, in accordance with certain aspectsand/or embodiments of the present inventions; although not illustrated,where the thermistor includes a plurality of micromachined thermistorstructures, such structures may be dispersed over or in the die tofacilitate acquisition of data which is may provide information which isrepresentative of (i) a temperature gradient in/on the die, (ii) hotspots in/on the die, and/or (iii) an average temperature across/inportions of the die;

FIGS. 14I-14K illustrate stacked die architectures wherein a thermistor(in accordance with aspects and/or embodiments of the presentinventions) fabricated, manufactured or integrated on a die alone orwith a MEMS device is stacked with a die having integrated circuitry, inaccordance with certain aspects and/or embodiments of the presentinventions; notably, all permutations and combinations of stacked diearchitectures including thermistors, MEMS devices and/or integratedcircuitry are intended to fall within the scope of the presentinventions;

FIG. 14L illustrate a stacked die architecture wherein a thermistor (inaccordance with aspects and/or embodiments of the present inventions)fabricated, manufactured or integrated on a die, is stacked with (i) adie having a MEMS device and (ii) a die having integrated circuitry, inaccordance with certain aspects and/or embodiments of the presentinventions;

FIG. 14M illustrates a stacked die architecture wherein a thermistor (inaccordance with aspects and/or embodiments of the present inventions) isfabricated, manufactured or integrated, with a MEMS device, on a diewhich includes (i) a thickness and/or (ii) a thermal insulating material(for example, a silicon nitride or silicon oxide) at the interface ofthe dice of the stacked die architecture that reduces and/or minimizesthe temperature gradient between the thermistor and the MEMS device dueto, for example, heat transfer from the die containing the integratedcircuitry, in accordance with certain aspects and/or embodiments of thepresent inventions;

FIG. 14N illustrates a stacked die architecture wherein a thermistorhaving a plurality of micromachined thermistor structures (in accordancewith aspects and/or embodiments of the present inventions) isfabricated, manufactured or integrated on a die with a MEMS device,wherein data from the thermistors may provide, for example, informationwhich is representative of (i) a temperature gradient in/on the die,(ii) hot spots in/on the die, and/or (iii) an average temperatureacross/in portions of the die, in accordance with certain aspects and/orembodiments of the present inventions;

FIGS. 14O and 14Q illustrate stacked die architectures wherein athermistor (in accordance with aspects and/or embodiments of the presentinventions) fabricated, manufactured or integrated on a die, is stackedside-by-side with a die having a MEMS device and on a die havingintegrated circuitry, in accordance with certain aspects and/orembodiments of the present inventions, wherein a thermal coupler (forexample, a thermally and/or electrically conductive epoxy (an “island”of such epoxy on or above the integrated circuit die that “bridges” bothdice or secures both dice to the integrated circuit die), metal trace orbar (which may be disposed on or suspended above the integrated circuitdie and “bridges” both dice to provide more extensive thermalcommunication between the dice of the thermistor and the MEMS device;

FIGS. 14P and 14R are cross-sectional views, along dotted line A-A, ofthe stacked die architectures of FIGS. 14O and 14Q, respectively,wherein the stacked architecture illustrated in FIG. 14P includes thedice of the MEMS device and the thermistor secured or fixed to anexposed surface of the package or die of the integrated circuit via anadhesive (for example, a thermally and/or electrically conductive epoxy)and the stacked architecture illustrated in FIG. 14R includes a thermalcoupler bridging the dice of the MEMS device and the thermistor, whereinthe thermal coupler may be, for example, a thermally and/or electricallyconductive epoxy (for example, an “island” of such epoxy on or above theintegrated circuit die that “bridges” both dice), which secures bothdice to the integrated circuit die and facilitates more extensivethermal communication between the dice of the thermistor and the MEMSdevice;

FIG. 14S illustrates stacked die architecture including a thermalcoupler and thermal isolator, wherein a thermistor (in accordance withaspects and/or embodiments of the present inventions) fabricated,manufactured or integrated on a die, is stacked side-by-side with a diehaving a MEMS device and on a thermal coupler which is disposed on athermal isolating material (for example, a polyimide film) which, inturn, is disposed on or above the die containing the integratedcircuitry, wherein the thermal coupler (for example, a metal film, or athermally and/or electrically conductive epoxy) provides more extensivethermal communication between the dice of the thermistor and the MEMSdevice and the thermal isolator reduces thermal transfer from theintegrated circuitry die to the MEMS device die and/or the thermistordie;

FIGS. 14T and 14U are cross-sectional views, along dotted line A-A, ofcertain embodiments of the stacked die architectures of FIG. 14S,wherein the cross-sectional view of FIG. 14T illustrates the dice of thethermistor and the MEMS device secured to the thermal coupler via, forexample, an adhesive (which may facilitate thermal communication to thethermal coupler (for example, a thermally and/or electrically conductiveepoxy) and the cross-sectional view of FIG. 14U illustrates anadhesive-thermal coupler (for example, a thermally and/or electricallyconductive epoxy) securing the dice of the thermistor and the MEMSdevice directly to a thermal isolating material (for example, apolyimide film) which is disposed on or above the integrated circuit;

FIG. 15A illustrates a cross-sectional view a micromachined thermistorstructure of a thermistor, according to one or more or the presentinventions, integrated in, on and/or above a substrate which includesone or more other structures (for example, one or more mechanicalstructures of a micro- or nano-electromechanical device), according toone or more of the present inventions; notably, in this illustratedembodiment, the other structure and thermistor are disposed in, onand/or above the substrate and formed (in whole or in part) in, onand/or from an active layer and in and/or on die; as such, the otherstructure (for example, MEMS or NEMS structure) and micromachinedthermistor structure are “coplanar” on the die;

FIG. 15B illustrates a cross-sectional view of a micromachinedthermistor structure of a thermistor, according to one or more or thepresent inventions, and a MEMS or NEMS structures, according to one ormore of the present inventions; notably, in this illustrativeembodiment, the MEMS/NEMS structure is fabricated, formed and/ordisposed in or from a first active layer and the micromachinedthermistor structure is fabricated, formed and/or disposed in or from asecond active layer (which, relative to the substrate base, may be aboveor below the first active layer; and, as such, the thermistor andMEMS/NEMS device are “stacked” on the same die;

FIG. 15C illustrates a cross-sectional view of two micromachinedthermistor structures of a thermistor, according to one or more or thepresent inventions, and a MEMS or NEMS structures, according to one ormore of the present inventions; notably, in this illustrativeembodiment, the MEMS/NEMS structure and one of the micromachinedthermistor structures are fabricated, formed and/or disposed in or froma first active layer, and a second micromachined thermistor structure isfabricated, formed and/or disposed in or from a second active layer(which, relative to the substrate base, may be above or below the firstactive layer; and, as such, the thermistor and MEMS/NEMS device arecoplanar and stacked on the same die;

FIG. 16 is a graphical illustration of a relationship of temperatureversus resistivity for different doping concentrations of asemiconductor material wherein DC4 is greater than DC3 is greater thanDC2 is greater than DC1; notably, using conventional doping techniques,the ability to control (within a predetermined tolerance or range) thedoping concentration DC4 is greater than DC3 is greater than DC2 isgreater than DC1, wherein the amount of doping (if any) of thethermistor may depend on or include competing consideration betweentemperature versus resistivity and controllability of the dopingprocesses and uniformity;

FIG. 17A illustrates, in block diagram form, a thermal coupler disposedbetween a MEMS device and a thermistor, to enhance the thermal couplingbetween the MEMS device with the thermistor, in accordance with certainaspects and/or embodiments of the present inventions;

FIGS. 17B-17D illustrate top views of exemplary lateral thermal couplersdisposed between exemplary thermistors and MEMS devices, according tocertain aspects and embodiments of the present inventions;

FIG. 17E illustrates, in a general diagram form, a vertical thermalcoupler disposed between a MEMS device and a thermistor, to thermalcouple the MEMS device with the thermistor, in accordance with certainaspects and/or embodiments of the present inventions;

FIG. 17F illustrates a cross-sectional view of a portion of the die ofFIG. 17E sectioned along A-A, wherein an exemplary vertical thermalcoupler is disposed between a portion of an exemplary thermistor and aportion of a MEMS device, according to certain aspects and embodimentsof the present inventions;

FIG. 17G illustrates, in a general diagram form, horizontal/lateral andvertical thermal couplers disposed between MEMS device(s) and athermistor, to thermally couple the MEMS device(s) with the thermistor,in accordance with certain aspects and/or embodiments of the presentinventions;

FIG. 18 illustrate a top view of exemplary an exemplary thermistor whichshares structural features with a MEMS device, according to certainaspects and embodiments of the present inventions;

FIGS. 19A and 19B illustrate discrete thermistor devices, in accordancewith aspects and/or embodiments of the present inventions, wherein thethermistor of FIG. 19A includes a micromachined metal thermistorstructure and FIG. 19B includes a micromachined metal thermistorstructure and a micromachined semiconductor thermistor structure;notably, although at times the description below may appear to bedirected to a micromachined semiconductor thermistor structure, theinventions, embodiments and features are entirely applicable to amicromachined metal thermistor structure and, although for the sake ofbrevity, the discussion is not repeated specifically in the context ofthe micromachined metal thermistor structure—one skilled in the artunderstands that such inventions, embodiments and features are entirelyapplicable to micromachined metal thermistor structure according to theaspects and embodiments of the present inventions;

FIGS. 20A-20D illustrate top views of exemplary thermistors according tocertain aspects and embodiments of the present inventions wherein theexemplary thermistor may include four or more anchors which secure,attach and/or physically couple the thermistor structure to thesubstrate, electrical contacts disposed or integrated in or on one ormore of the anchors, and a micromachined thermistor structure includes(i) a loop-shape and, in FIGS. 20A and 20B, (ii) a serpentine orundulating shape;

FIGS. 21A-21F illustrate top views of exemplary thermistors according tocertain aspects and embodiments of the present inventions wherein theexemplary thermistor are released via the vents; the vents may belocated (i) directly over portions of the micromachined thermistorstructure (see FIGS. 21A, 21B and 21D), and/or (ii) remote from portionsof the micromachined thermistor structure (see FIG. 21C), and/or (iii)adjacent to portions of structure 12 (see FIGS. 21E and 21F)

FIGS. 22A-22F illustrate cross-sectional views, along dotted line A-A ofthe exemplary thermistor illustrated in FIG. 21D, at various stages ofmanufacturing, wherein FIG. 22A illustrates a cross-sectional view ofthe micromachined thermistor structure after formation and prior torelease from the substrate, FIG. 22B illustrates a cross-sectional viewof the micromachined thermistor structure after providing or depositinga sacrificial layer on the micromachined thermistor structure, FIG. 22Cillustrates a cross-sectional view after forming, depositing, growingand/or providing an encapsulation layer on and/or over sacrificial layerand prior to release of the micromachined thermistor structure from thesubstrate (via removal or etching of the sacrificial layer from aroundthe micromachined thermistor structure), FIG. 22D illustrates across-sectional view after forming vents in the encapsulation layer,FIG. 22E illustrates a cross-sectional view after releasing of themicromachined thermistor structure from the substrate wherein thesacrificial layer is removed or etched from around micromachinedthermistor structure thereby substantially or entirely releasing(vertically and horizontally) micromachined thermistor structure; in oneembodiment, the vents are closed and the cavity sealed after releasingmicromachined thermistor structure, for example, via deposition forming,depositing, growing and/or providing another encapsulation layer (seeFIG. 22F);

FIGS. 23A-23D illustrate top views of exemplary thermistors according tocertain aspects and embodiments of the present inventions wherein theexemplary thermistor may include two electrical contacts and amicromachined thermistor structure includes (i) a loop-shape and, inFIGS. 23A and 23B, (ii) a serpentine or undulating shape;

FIGS. 24A and 24B illustrate top views of exemplary thermistorsaccording to certain aspects and embodiments of the present inventionswherein the exemplary micromachined thermistor structure includes (i) aloop-shape and (ii) a serpentine or undulating shape; and

FIGS. 25A-25C illustrate micromachined thermistor structures includingloop-shapes having different bending radii wherein FIG. 25A includes asharper bending radius in relation to the bending radius of theloop-shape of FIGS. 25B and 25C; notably, it may be advantageous toincrease the bending radius of a loop-shape to facilitate more uniformcurrent flow throughout the micromachined thermistor structure and inparticular, through the loop-shape portion of the micromachinedthermistor structure.

Again, there are many inventions described and illustrated herein. Thepresent inventions are neither limited to any single aspect norembodiment thereof, nor to any combinations and/or permutations of suchaspects and/or embodiments. Each of the aspects of the presentinventions, and/or embodiments thereof, may be employed alone or incombination with one or more of the other aspects of the presentinventions and/or embodiments thereof. For the sake of brevity, many ofthose combinations and permutations are not discussed separately herein.

DETAILED DESCRIPTION

There are many inventions described and illustrated herein. In oneaspect, the present inventions are directed to a thermistor and themethod of manufacturing a thermistor which includes a predeterminedand/or high correlation of resistance to ambient temperature and,preferably, limited, minimum and/or reduced stress-resistancedependence. In one embodiment, the thermistor includes a micromachinedthermistor structure which is fabricated from a temperature-sensitivecrystalline material (for example, doped or undoped semiconductormaterial(s) such as, for example, monocrystalline, polycrystallineand/or amorphous silicon, germanium, silicon/germanium, silicon carbide(SiC), and gallium arsenide). For example, in one embodiment, themicromachined thermistor structure may be fabricated or formed from adoped monocrystalline or polycrystalline silicon (for example, dopedwith a p-type impurity (such as, for example, boron, aluminum, or otherelement in group 13 of the periodic table as well as compounds) or ann-type impurity (such as, for example, phosphorus and/or arsenic) usingwell-known deposition, lithographic, etching and/or doping techniques.

In addition thereto, or in lieu thereof, in another embodiment, thethermistor may include one or more micromachined thermistor structureswhich is/are fabricated from a metal material (for example, platinum,aluminum, molybdenum and/or copper (or alloys thereof)). For example, inone embodiment, the micromachined thermistor structure may be fabricatedor formed from platinum and/or copper (or alloys thereof) usingwell-known deposition, lithographic, and/or etching techniques. Indeed,in another embodiment, the thermistor includes a plurality of thermistorstructures including a first micromachined thermistor structurefabricated from a doped monocrystalline or polycrystalline semiconductormaterial and a second micromachined thermistor structure fabricated froma metal material.

With reference to FIGS. 1A, 2A-2C and 3A-3E, in exemplary embodiments,thermistor 10 includes a micromachined thermistor structure 12 which isdisposed on, above and/or in substrate 14. In this exemplary illustratedembodiment, micromachined thermistor structure 12 is disposed abovesubstrate 14. In this regard, micromachined thermistor structure 12 issubstantially or entirely released (vertically and horizontally),suspended, and/or “free-standing” relative to substrate 14. In this way,the impact of internal or external stress introduced during operation onthe temperature dependent characteristics (for example, resistance) ofmicromachined thermistor structure 12 is limited, reduced and/orminimized (relative to, for example, micromachined thermistor structure12 that is disposed in substrate 14). That is, the temperature dependentcharacteristics (for example, resistance) of micromachined thermistorstructure 12, which is released (vertically and/or horizontally),suspended, and/or “free-standing” relative to the substrate, arerelatively and/or substantially independent of internally or externallyinduced stresses in substrate 14 and, as such, provide a more accurateand/or reliable representation of the ambient temperaturenotwithstanding any non-temperature related/dependent ambient operatingconditions of thermistor 10 (for example, substrate stress or forces(internal or external) applied thereto).

With reference to FIGS. 2A-2C and 4A, thermistor 10 may be formed in oron substrate 14. The substrate 14 may be, for example, a doped orundoped semiconductor material, a glass material, or an insulatormaterial. For example, substrate 14 may be a portion of asemiconductor-on-insulator wafer or a portion of a standard type waferhaving active layer 14 c disposed on sacrificial layer 14 b (forexample, a silicon oxide or silicon nitride) which is disposed onsubstrate base 14 a (which may be a semiconductor, a glass, or aninsulator). With reference to FIGS. 2A-2C, 4A and 4B, micromachinedthermistor structure 12 may be defined or formed in active layer 14 c(for example, a semiconductor or metal) using well-known lithographicand etching techniques. Thereafter, layer 14 b (for example, insulatoror sacrificial layer of substrate 14) may be removed or etched therebypartially, substantially or entirely releasing (vertically and/orhorizontally) micromachined thermistor structure 12 (in whole or inpart) from substrate 14 (which, in the illustrated embodiment, includessubstrate base 14 a). (See, FIG. 4C). Notably, micromachined thermistorstructure 12 may be fabricated using any processing or fabricationtechniques now known or later developed.

With reference to FIGS. 2A-2C, micromachined thermistor structure 12 mayinclude portions that include one or more loop-shapes, linear orstraight, or curved and/or undulating, or, as discussed in connectionwith other embodiments, combinations thereof. Where micromachinedthermistor structure 12 includes loop-shape anchors 16 of thermistor 10may be located in close proximity. That is, with reference to FIGS. 2Aand 3A, in this exemplary illustrated embodiment, micromachinedthermistor structure 12 includes a loop-shape wherein anchors 16 arelocated in close proximity. In this embodiment, anchors 16 secure,attach and/or physically couple the micromachined thermistor structure12 to substrate 14. In this way, displacement of or impact onmicromachined thermistor structure 12 (or portions thereof) due tointernal or external stress may be limited, minimized and/or reducedthereby limiting and/or reducing the impact of such forces on thetemperature dependent output signal of thermistor 10.

Moreover, a loop-shape (wherein anchors 16 of micromachined thermistorstructure 12 are located in close proximity) may increase the rigidity,restoring force and/or resonant frequency of micromachined thermistorstructure 12 of the thermistor 10 in response to, for example, internalor external forces applied to substrate 14 (e.g.,vibration)—particularly in those embodiments where micromachinedthermistor structure 12 is partially, substantially or entirely released(vertically and/or horizontally), suspended, or “free-standing” relativeto substrate 14 (which improves the accuracy and/or reliability of thetemperature dependent output signal of thermistor 10). In oneembodiment, micromachined thermistor structure 12 includes a resonantfrequency of greater than 200 kHz, and preferably greater than 500 kHz.

Notably, a higher rigidity, restoring force and/or resonant frequency ofmicromachined thermistor structure 12 may increase the restoring forceand, as such, reduce, minimize and/or eliminate stictionconcerns—wherein micromachined thermistor structure 12 may physicallycontact and “attach” to a nearby structure/material (for example, activelayer 14 c, substrate base 14 a and/or a cover (in those embodimentswhere the micromachined thermistor structure of the thermistor isencapsulated or a cover is disposed over the micromachined thermistorstructure)). As such, in those embodiments where micromachinedthermistor structure 12 is partially, substantially or entirely released(vertically and/or horizontally), suspended, or “free-standing” relativeto substrate 14, it may be advantageous to include a physical design ofmicromachined thermistor structure 12 that the rigidity, restoring forceand/or resonant frequency of the micromachined thermistor structure 12be greater than the impact of estimated or anticipated externally forcesto or vibration of thermistor 10. In this way, the restoring force ofmicromachined thermistor structure 12 of thermistor 10 will reduce orminimize stiction concerns.

With reference to FIGS. 2A-2C, 3A and 3E, thermistor 10 also includeselectrical contacts 18 to, for example, couple to measurement circuitry100. (See, for example, FIGS. 1B-1F). In certain embodiments, electricalcontacts 18 are integrated or disposed in or on anchor 16 of thermistor10. For example, with reference to FIGS. 2A-2C, 3A and 3E, electricalcontacts 18 are integrated or disposed in or on anchors 16 of thermistor10. The thermistor 10 may employ any design, form or type of electricalcontact now known or later developed to facilitate acquisition of thetemperature dependent output signal of thermistor 10; that is, theoutput signal which is representative of the ambient temperature ofmicromachined thermistor structure 12.

With reference to FIGS. 2A-2C, 3A-3E and 4A-4C, the material(s)comprising micromachined thermistor structure 12 may include one or moreimpurity dopants. The impurity dopant may be acceptor type(s) or donortype(s). Moreover, the impurity dopant(s) may be introduced into activelayer 14 c during formation of layer 14 c and/or at any stage of thefabrication process, including, for example, at stages FIGS. 4A, 4Band/or 4C. Any technique now known or later developed may be employed toincorporate one or more dopants into the material(s) comprisingmicromachined thermistor structure 12.

The impurity dopant type and/or doping levels thereof (both of which maydepend on a given base or substrate material of the structure) may beselected to provide a predetermined, increased, enhanced and/or maximumsensitivity of the temperature dependent characteristic of the structure(for example, resistance). In one embodiment, the micromachinedthermistor structure is doped with a dopant type and/or at doping levelsthat provide a predetermined and/or maximum increase in sensitivity ofthe temperature dependent characteristic of the structure (for example,resistance) in relation to or versus a predetermined and/or minimumsensitivity to doping variations (which may also depend on manufacturingcontrollability and/or tolerances of the doping operation). (See, forexample, FIG. 16). Here, although the dopant and/or dopingconcentrations may not provide a maximum sensitivity and/or linearity ofthe temperature dependent characteristic of the micromachined thermistorstructure (see, for example, DC1 in FIG. 16), such dopant and/or levelsmay provide an increase in the temperature dependent characteristic,relative to other doping concentrations or levels (for example, alightly or an undoped base material) of the structure, and a sensitivityand/or linearity of the temperature dependent characteristic (forexample, resistance) over manufacturing variations or tolerances indoping operations/concentrations is within a predetermined and/oracceptable range or limits (see, for example, DC2 in FIG. 16).

For example, in one embodiment, the micromachined thermistor structuremay be fabricated or formed from a doped monocrystalline orpolycrystalline silicon (for example, doped with a p-type impurity (suchas, for example, boron, aluminum, or other element in group 13 of theperiodic table as well as compounds (for example, boron difluoride, BF₂)having acceptor type characteristics)) using well-known fabricationtechniques (including deposition, lithographic, etching and/or dopingtechniques). It may be advantageous to implement boron doping levels ina silicon material which provides an impurity concentration of greaterthan 10¹⁶ cm⁻³ and less than 10¹⁸ cm⁻³. In this way, the sensitivity ofthe resistance of the micromachined thermistor structure, over a certaintemperature range (Ta to Tc), is relatively linear.

Notably, in one embodiment, the doping processes of the micromachinedthermistor structure may include a plurality of impurity dopant typesand/or a plurality of doping levels, which, in sum, provide a net dopingconcentration. In one embodiment, the doping processes may include (i) afirst impurity dopant type at first doping level and (ii) a secondimpurity dopant type (which is the same impurity type as the firstimpurity dopant type—for example, boron, aluminum and gallium) at asecond doping level. In another embodiment, the doping processes mayinclude counter-doping which includes (i) a first impurity dopant typeat first doping level and (ii) a second impurity dopant type (which isopposite the first impurity dopant type—for example, boron andphosphorus) at a second doping level. Here, the dominant impurity typeand the net doping concentration of the micromachined thermistorstructure are dependent on, among other things, the impurity dopanttypes and the doping levels of such impurities.

In another embodiment, the doping processes of the thermistor mayprovide a first region of the thermistor (for example, the electricalcontacts) having first impurity dopant type(s) and/or first impuritydoping level(s), and a second region of the thermistor (for example, themicromachined thermistor structure) having second impurity dopanttype(s) and/or second impurity doping level(s). For example, in a regionin and/or around the electrical contacts, the doping concentration maybe heavier relative to the micromachined thermistor structure which islightly doped to increase the sensitivity to variations in temperature.Moreover, the heavily doped regions (electrical contact and, in certainembodiments, the anchors) are less sensitive to local stress and tend toinclude a greater electrical and thermal conductivity.

Notably, all permutations and combinations of doping properties (forexample, implantation strength/energy), impurity dopant types and/or aplurality of doping levels/concentrations are intended to fall withinthe scope of the present inventions.

With reference to FIG. 5A, in one embodiment, micromachined thermistorstructure 12 of thermistor 10 may include (in whole or in part) aserpentine or undulating shape (see area 20). For example, wheremicromachined thermistor structure 12 includes a loop-shape, one or moreof the legs or portions of the loop-shape of the micromachinedthermistor structure may include a serpentine or undulating shape orportion 20 to, among other things, increase the sensitivity of thesignal corresponding to the temperature dependent characteristics ofmicromachined thermistor structure 12, increase resistance ofmicromachined thermistor structure 12, and/or limit and/or reduce theimpact on micromachined thermistor structure 12 (or portions thereof) ofinternal or external forces (for example, stress and/or vibration). Theserpentine or undulating portion 20 of micromachined thermistorstructure 12 may be substantially or entirely released (vertically andhorizontally), suspended, and/or “free-standing” relative to substrate14. (See, FIG. 6A wherein portion 20 of micromachined thermistorstructure 12 is vertically and horizontally released from thesubstrate). The serpentine or undulating portion 20 of micromachinedthermistor structure 12 may limit, reduce and/or minimize the impact ofinternal or external stresses introduced during operation ofmicromachined thermistor structure 12 (for example, the stictionattributes or characteristics of micromachined thermistor structure 12).

With continued reference to FIG. 5A, in one embodiment, micromachinedthermistor structure 12 includes symmetry of one or more major portionsof the loop-shape of the micromachined thermistor structure (forexample, in relation to an axis of the structure—symmetry axis 20 inFIG. 5A). Here, the major portions of the loop-shape include symmetricalor substantially symmetrical serpentine or undulating shapes.

The thermistor 10 may include two or more electrical contacts 18 toinput and/or output signals from the thermistor. (See, FIGS. 2A-2C and5A-5C). The electrical contacts 18 facilitate measurement of atemperature dependent characteristics of the micromachined thermistorstructure (and/or change therein) of thermistor 10. In one embodiment,thermistor 10 includes two electrical contacts 18 (see, for example,FIGS. 2A-2C and 5A) to facilitate a 2-point sensingconfiguration/architecture where measurement circuitry samples, detectsand/or measures the temperature dependent characteristics (and/orchanges therein) of the micromachined thermistor structure 12 (forexample, resistance or change in resistance of micromachined thermistorstructure 12). (See, FIG. 7A). In another embodiment, thermistor 10includes four electrical contacts 18 (see FIGS. 5B and 5C) to facilitateimplementation of 2-point or 4-point sensingconfigurations/architectures wherein a 4-point sensingconfiguration/architecture may facilitate more accurate measurement ofthe temperature dependent characteristics (for example, resistance),and/or change therein, of thermistor 10 with minimal, reduced, little orno contribution to the overall or measured resistance due to, forexample, (i) the electrical contacts or signal path to the measurementcircuitry and/or (ii) non-idealities of the measurement circuitry. (See,for example, FIG. 7B). In one embodiment, a current (I) is applied tothermistor 10 through F+/F− electrical contacts (via the currentsource), and the resulting voltage is sensed at the S+/S− electricalcontacts (via the voltage measurement circuitry). The voltagemeasurement circuit may be designed to include a large or high inputimpedance so that little to no current flows in/out of the S+/S− orelectrical contacts thereby facilitating a highly accurate measurementof the resistance (or change therein) of thermistor 10.

In yet another embodiment, thermistor 10 includes three electricalcontacts 18 (see, FIG. 5D) to facilitate implementation of 2-point or3-point sensing configurations/architectures wherein in a 3-pointmeasurement architecture/configuration, the measuring circuitry measuresa resistance or changes in resistance of the thermistor wherein theresistance of the thermistor is determined by applying/forcing acurrent, I, across the F+/F− terminals, and sensing a voltage, V, acrossthe S+/S− terminals (see, for example, FIG. 7C). Like a 4-point sensingconfiguration/architecture, a 3-point sensing configuration/architecturemay facilitate more accurate measurement of the temperature dependentcharacteristics (for example, resistance), and/or change therein, ofthermistor 10 with minimal, reduced, little or no contribution to theoverall or measured resistance due to, for example, (i) the electricalcontacts or signal path to the measurement circuitry and/or (ii)non-idealities of the measurement circuitry. Here again, the voltagemeasurement circuit may be designed to include a large or high inputimpedance so that little to no current flows in/out of the S+/S− orelectrical contacts thereby facilitating a highly accurate measurementof the resistance (or change therein) of thermistor 10.

Notably, the present inventions may employ any measuring technique orarchitecture now known or later developed. For example, a bridge-typecircuit (See, for example, FIG. 7D) may be employed to determine thetemperature dependent characteristics of the micromachined thermistorstructure and/or change therein (for example, resistance) wherein atleast one portion of the bridge corresponds to the temperature dependentparameter of the micromachined thermistor structure.

In one embodiment, one or more of the electrical contacts 18 ofthermistor 10 are physically integrated or disposed in one or more ofanchors 16 of thermistor 10. (See, FIGS. 2A-2C, 3A, 3E, 5A and 5B).However, in other embodiment, one or more (or all) of the electricalcontacts 18 are not physically integrated or disposed in one or more ofanchors 16 of thermistor 10. (See, FIGS. 5C and 5D). The anchors 16 andelectrical contacts 18 may be fabricated using any technique and/ormaterial now known or later developed; in one embodiment, such anchorsand contacts are fabricated using the techniques and/or materialsdescribed and/or illustrated in U.S. Pat. No. 6,936,491.

The micromachined thermistor structure 12 may be sealed or encapsulatedin a chamber—thereby protecting micromachined thermistor structure 12from the external environment and/or controlling theenvironment/conditions (for example, pressure) in which micromachinedthermistor structure 12 operates/resides. Indeed, prior to, duringand/or after sealing the chamber, the environment within the chamber maybe defined, for example, via materials and processing techniques thatprovide predetermined characteristics of the environment in the chamber,for example, predetermined pressure and/or fluid (for example, an inertgas or anti-stiction fluid). (See, for example, U.S. Pat. Nos.6,930,367, 7,449,355 and 7,514,283). Such a configuration reduces thelikelihood of contamination of the components of thermistor 10,including micromachined thermistor structure 12, which may improvestability and reliability of thermistor 10. Notably, the environmentwithin the chamber may be defined using any technique now known or laterdeveloped.

In one embodiment, micromachined thermistor structure 12 may be sealedin a cavity via thin-film encapsulation process and structure. (See,FIG. 8A). Briefly, in one exemplary embodiment, after definingmicromachined thermistor structure 12 (see FIGS. 5A and 9A), a processof fabricating a thin-film encapsulation structure starts withdepositing or providing sacrificial layer 24 over micromachinedthermistor structure 12 (see FIG. 9B). Thereafter, layer 26 is provided,for example, formed, deposited and/or grown (see FIG. 9C). Vents (notillustrated in this series of figures) are then formed in encapsulationlayer 26 and the sacrificial layer 24 is removed or etched aroundmicromachined thermistor structure 12 thereby substantially or entirelyreleasing (vertically and horizontally) micromachined thermistorstructure 12. (See, FIG. 9D). As noted above, in this way, the impact ofinternal or external stresses introduced during operation on thetemperature dependent characteristics (for example, resistance) ofmicromachined thermistor structure 12 is limited, reduced and/orminimized (relative to, for example, micromachined thermistor structure12 that is disposed in substrate 14). That is, the temperature dependentcharacteristics (for example, resistance) of micromachined thermistorstructure 12, which is released (vertically and/or horizontally),suspended, and/or “free-standing”, are relatively and/or substantiallyindependent of internally or externally induced stresses in substrate 14and, as such, provide a more accurate and/or reliable representation ofthe ambient temperature notwithstanding any non-temperaturerelated/dependent ambient operating conditions of thermistor 10 (forexample, substrate stress or forces (internal or external) appliedthereto).

After releasing micromachined thermistor structure 12, in oneembodiment, the vents may be closed and the cavity sealed via anotherdeposition of a layer 28. (See, FIG. 9E). A detailed discussion of anexemplary thin film encapsulation technique is described and illustratedin U.S. Pat. Nos. 6,936,491, 7,075,160, and 7,514,283. Notably, themicromachined thermistor structure may be sealed or encapsulated usingany technique now known or later developed. In one embodiment, the ventsmay be sealed via attaching a die, wafer or glass substrate (which mayinclude other structures or integrated circuitry thereon) toencapsulation layer 26.

In one embodiment, micromachined thermistor structure 12 is unsealed ornot encapsulated and thereby directly exposed to the externalatmosphere/environment. Indeed, in those embodiments where micromachinedthermistor structure 12 is unsealed or not encapsulated, it may beadvantageous to include a passivation layer on micromachined thermistorstructure 12. (See, FIG. 6B). In one embodiment, the passivation layeris a silicon oxide and/or a silicon nitride material which is depositedor thermally grown. Such a passivation layer may improve long termstability of the thermistor wherein the relationship between temperatureand resistance is more stable over the life of the thermistor.

With reference to FIG. 6C, in another embodiment, a passivation material(for example, a compliant like material such as a gel, soft plastic orrubber-like material (for example, silicon rubber)) may be employed toprotect micromachined thermistor structure 12 and improve long termstability of thermistor 10 (wherein the temperature dependentcharacteristics of the thermistor may be more stable over time (forexample, less change in resistance over time). The passivation materialof this embodiment is selected and/or applied in such a manner as to notcommunicate appreciable stress to the micromachined thermistorstructure. In this way, the impact of internal or external stressintroduced into micromachined thermistor structure 12 as a result of thepassivation is limited and/or managed in relation to the temperaturedependent output signal.

In another embodiment, micromachined thermistor structure 12 may besealed, for example, in a TO-8 “can” (or like structure) and/or in acavity via a wafer or glass substrate 30 bonded to the thermistor die orsubstrate. (See, FIG. 8B). In this regard, micromachined thermistorstructure 12 may be sealed in a chamber, for example, a hermeticallysealed metal container (see, for example, U.S. Pat. No. 6,307,815) orbonded to a semiconductor, metal or glass-like substrate having achamber to house, accommodate or cover micromachined thermistorstructure 12 (see, for example, U.S. Pat. Nos. 6,146,917, 6,352,935,6,477,901, and 6,507,082). In the context of the hermetically sealedmetal container, the substrate on, or in which, the resistive structurewould reside may be disposed in and affixed to the metal container. Thehermetically sealed metal container typically serves as a primarypackage as well.

Notably, as intimated above, after or during sealing of the chamber, ananti-stiction fluid may be incorporated into the chamber. (See, forexample, U.S. Pat. Nos. 6,930,367 and 7,449,355). In this way, theanti-stiction characteristics of the micromachined thermistor structureof the thermistor may be enhanced. Indeed, gases (for example, argon,nitrogen and/or helium) may be trapped within the chamber

With reference to FIGS. 10A and 10B, the serpentine or undulating shapeof micromachined thermistor structure 12 may be symmetrical about axis22. In this embodiment, micromachined thermistor structure 12 includes aloop-shape, wherein both legs or portions of the loop-shape of themicromachined thermistor structure include a serpentine or undulatingshape or portion 20 to, among other things, increase the sensitivity ofthe signal corresponding to the temperature dependent characteristics ofmicromachined thermistor structure 12, increase resistance ofmicromachined thermistor structure 12, and/or limit and/or reduce theimpact on micromachined thermistor structure 12 (or portions thereof) ofinternal or external forces (for example, stress and/or vibration). Inthis embodiment, the serpentine or undulating portion 20 ofmicromachined thermistor structure 12 are substantially or entirelyreleased (vertically and horizontally), suspended, and/or“free-standing” relative to substrate 14. (See, FIG. 11A wherein portion20 of micromachined thermistor structure 12 is vertically andhorizontally released from substrate). It should be noted thatmicromachined thermistor structure 12 may include any shape orconfiguration now known or later developed.

With reference to FIG. 10A, thermistor 10 may include one or moreanchors that are displaced relative to the signal flow (for example,current flow) through or in the micromachined thermistor structure.(See, anchor 16 and signal I_(signal)) In this way, the impact ofinternal or external stress introduced into the micromachined thermistorstructure via anchor 16 are limited, minimized and/or reduced inrelation to the temperature dependent output signal (I_(signal)). Thatis, locating the anchors distant from the path of the signal flow usedin connection with the measurement of the temperature dependentcharacteristics (for example, resistance) of micromachined thermistorstructure 12, the output of micromachined thermistor structure 12provides a more accurate and/or a more reliable representation of theambient temperature regardless of the non-temperature related/dependentambient operating conditions of thermistor 10 (for example, substratestress or forces (internal or external) applied thereto).

As indicated above, micromachined thermistor structure 12 may includeany shape now known or later developed including a shape which is not aloop-shape. (See, for example, FIGS. 12A-12E). Here, anchors 16 ofthermistor 10 (which secure, attach and/or physically couple themicromachined thermistor structure 12 to substrate 14) are not locatedin close proximity so as to form a loop-shape. In these embodiment,micromachined thermistor structure 12 is substantially or entirelyreleased (vertically and horizontally), suspended, and/or“free-standing” relative to substrate 14. (See, the cross-sectional viewof FIGS. 13A and 13B). In this way, the impact of internal or externalstresses introduced during operation on the temperature dependentcharacteristics (for example, resistance) of micromachined thermistorstructure 12 is limited, reduced and/or minimized (relative to, forexample, micromachined thermistor structure 12 that is disposed insubstrate 14). That is, the temperature dependent characteristics (forexample, resistance) of micromachined thermistor structure 12, which isreleased (vertically and/or horizontally), suspended, and/or“free-standing” relative to the substrate, are relatively and/orsubstantially independent of internally or externally induced stressesin substrate 14 and, as such, provide a more accurate and/or reliablerepresentation of the ambient temperature notwithstanding anynon-temperature related/dependent ambient operating conditions ofthermistor 10 (for example, substrate stress or forces (internal orexternal) applied thereto).

Notably, micromachined thermistor structure 12, regardless of shape,configuration and/or architecture, may be sealed or encapsulated in achamber—thereby protecting micromachined thermistor structure 12 fromthe external environment and/or controlling the environment/conditions(for example, fluid and pressure) in which micromachined thermistorstructure 12 operates/resides. Any encapsulation technique, now known orlater developed, may be employed. (See, for example, the cross-sectionalview of an exemplary thin film encapsulation technique in FIG. 11B thecross-sectional view of a “can” (or like structure) and/or in wafer, dieor glass substrate bonded to the thermistor die or substrate in FIG.11C, each being in relation to the exemplary illustrated embodiment ofmicromachined thermistor structure 12 of FIG. 10).

The thermistor of the present inventions may be a discrete device. Forexample, thermistor 10 may be formed in and/or on die 34 (for example,any of the embodiments described and/or illustrated herein, includingany combinations and permutations thereof). (See, for example, FIG.14A). The thermistor 10 may include one or more micromachined thermistorstructures 12. (See, for example, FIGS. 14A and 14B). Where thethermistor includes a plurality of micromachined thermistor structures,the circuitry (for example, data processing circuitry) may calculate,assess and/or determine (i) a temperature gradient in/on die 34, (ii)hot spots in/on die 34, and/or (iii) an average temperature across/inportions of die 34. In this regard, the circuitry may receive aplurality of data samples which are indicative or representative oftemperature and which correspond to a plurality of different spatialregions in/on die 34 and, in response thereto, calculate and/ordetermine a temperature gradient in/on die 34, identify hot spots in/ondie 34, and/or calculate and/or determine an average temperatureacross/in portions of die 34, for example, a given time.

Notably, techniques and/or circuitry of the present inventions mayimplement any form of averaging. For example, the techniques and/orcircuitry of the present inventions may spatially average thetemperature dependent data from the micromachined thermistor structures.In addition thereto, or in lieu thereof, the techniques and/or circuitrymay temporally average the temperature dependent data from themicromachined thermistor structures. The temporal averaging may beimplemented via low-pass filtering including multi-order filters suchas, for example, one or more second-order Butterworth-type filters).

In another embodiment, one or more micromachined thermistor structures12 may be integrated in, on and/or above a substrate 14 which includesone or more other structures (for example, one or more mechanicalstructures of a micro- or nano-electromechanical device (MEMS or NEMSdevice, respectively, hereinafter collectively “MEMS device”)). Here,both MEMS device 36 (which includes a MEMS structure 38 and, in certainembodiments, drive and/or sense electrodes 40) and thermistor 10 (havingone or more micromachined thermistor structures) are disposed in, onand/or above substrate 14 and formed in, on and/or from (for example, asdescribed herein) active layer 14 c and in and/or on die 34. (See, FIGS.14C-14E and 15A). In one embodiment, MEMS structure 38 and micromachinedthermistor structure 12 are fabricated, formed and/or disposed in orfrom, in whole or in part, in active layer 14 c, and, as such, MEMSstructure 38 and micromachined thermistor structure 12 may be considered“coplanar configuration”. (See, FIG. 15A). In another embodiment, MEMSstructure 38 is fabricated, formed and/or disposed in or from a firstactive layer and micromachined thermistor structure 12 is fabricated,formed and/or disposed in or from a second active layer (which, relativeto the substrate base, may be above or below the first active layer).(See, FIG. 15B). In this way, thermistor 10 and MEMS device 36 arefabricated and/or arranged in a “stacked configuration” on die 34 suchthat MEMS structure 38 and micromachined thermistor structure 12 arefabricated, formed and/or disposed in or from different active layers.

With reference to FIGS. 14D and 14E, thermistor 10 includes a pluralityof micromachined thermistor structures 12 and, as such, the circuitry(for example, data processing circuitry) may calculate, assess and/ordetermine (i) a temperature gradient in/on die 34 (including across MEMSstructure 38 of MEMS device 36), (ii) hot spots in/on die 34, and/or(iii) an average temperature across/in portions of die 34 (including inrelation to MEMS structure 38 of MEMS device 36). Here, circuitry mayreceive a plurality of data samples which are indicative orrepresentative of temperature and correspond to a plurality of differentspatial regions in/on die 34 and calculate and/or determine temperaturerelated data (for example, the gradient in/on die 34, hot spots in/ondie 34 and/or an average temperature across/in portions of die 34). Inresponse, the circuitry may control or adjust the control of othercircuitry (for example, the clock generation circuitry—see, for example,FIGS. 1D-1F).

In yet another embodiment, thermistor 10 and MEMS device 36 arefabricated in a coplanar configuration and a stacked configuration. Inthis regard, a first thermistor structure 12 a and MEMS structure 38 arefabricated, formed and/or disposed in or from active layer 14 c, and asecond thermistor structure 12 b is fabricated, formed and/or disposedin a different active layer (which, relative to the substrate base, maybe above or below the first active layer). (See, for example, FIG. 15C).

With continued reference to FIG. 15A-15C, micromachined thermistorstructure 12, regardless of shape, configuration, architecture,integration and/or packaging, may be sealed or encapsulated in achamber—thereby protecting micromachined thermistor structure 12 fromthe external environment and/or controlling the environment/conditions(for example, fluid and pressure) in which micromachined thermistorstructure 12 operates/resides. Any encapsulation technique, now known orlater developed, may be employed. (See, for example, the cross-sectionalview of an exemplary thin film encapsulation technique in FIG. 11B thecross-sectional view of a “can” (or like structure) and/or in wafer, dieor glass substrate bonded to the thermistor die or substrate in FIG.11C).

Notably, where micromachined thermistor structure 12 is integrated witha MEMS structure 38, in one embodiment, the dopant type and/or dopingconcentrations employed in connection with fabricating micromachinedthermistor structure 12 may be different from the dopant type and/ordoping concentrations employed in connection with the MEMS structure 38.For example, in one embodiment, micromachined thermistor structure 12may include a first doping type or dopant (for example, a p-typeimpurity (such as, for example, boron) and MEMS structure 38 may includea second doping type or dopant (for example, an n-type impurity (suchas, for example, phosphorus and/or arsenic). In another embodiment,micromachined thermistor structure 12 may include a first doping type(for example, a p-type impurity (such as, for example, boron) and at afirst doping concentration, and MEMS structure 38 may include the samedoping type (for example, p-type impurity) but at a second dopingconcentration. That is, with reference to FIG. 16, the dopingconcentration of micromachined thermistor structure 12 may be at a firstrange or level (for example, see DC1 or DC2) and the dopingconcentration of MEMS structure 38 may be at a second range or level(for example, see, DC4).

The different doping types and/or concentrations of the micromachinedthermistor structure and the MEMS structure may be implemented usingconventional processing techniques. For example, during doping of themicromachined thermistor structure or MEMS structure, the other isprotected via a mask. All techniques for controlling the dopant typeand/or doping concentrations in connection with micromachined thermistorstructure and the MEMS structure are intended to fall within the scopeof the present inventions.

It should be noted that MEMS device 36 may include one or more MEMSstructures and may be, for example, one or more gyroscopes, resonators,pressure sensors and/or accelerometers, made in accordance withwell-known fabrication techniques, such as lithographic and otherprecision fabrication techniques, which form mechanical components to ascale that is generally comparable to microelectronics. Indeed, MEMSdevice 36 may be or may include any MEMS structure now known or laterdeveloped.

With reference to FIGS. 14F and 14G, thermistor 10 (which, in FIG. 14Fincludes one thermistor structure and in FIG. 14G includes twothermistor structures; as noted above, thermistor 10 may include morethan two structures) may be integrated with circuitry 42 as anintegrated circuit type device. In this regard, thermistor 10 of any oneor more embodiments of the present inventions may be integrated on die34 including integrated circuitry 42. The integrated circuitry 34 may beany circuitry now known or later developed. Indeed, the integratedcircuitry may be measurement circuitry, data processing circuitry and/orclock generation circuitry. (See, for example, FIGS. 1B-1F).

Briefly, with continued reference to FIGS. 1B-1F, the measurementcircuitry receives the output(s) of thermistor 10 and generates datawhich is representative of the temperature of the micromachinedthermistor structure. The data processing circuitry receives the outputof the measurement circuitry and processes the measured value(s). In oneembodiment, the data processing circuitry includes analog-to-digitalcircuitry (A/D converter) to generate a digital representation of themeasured value. See, for example, FIGS. 1C-1F). The data processingcircuitry may also include circuitry to calculate one or more parametersor values for clock generation circuitry to generate parameters orvalues for a given operating temperature and/or compensate for changesin the operating temperature. (See, for example, FIGS. 1D-1F and U.S.Pat. No. 6,995,622). In this regard, where the MEMS device is a MEMSresonator, the data processing circuitry may generate one or moretemperature dependent parameters or values for the clock generationcircuitry.

For example, where the clock generation circuitry includes one or morephase locked loops (PLLs), delay locked loops (DLLs), digital/frequencysynthesizer (for example, a direct digital synthesizer (“DDS”),frequency synthesizer, fractional synthesizer and/or numericallycontrolled oscillator) and/or frequency locked loops (FLLs), the dataprocessing circuitry may employ the data which is representative of thetemperature of the micromachined thermistor structure to adjust theparameters or values applied to such circuitry based on a measuredoperating temperature and/or changes in the operating temperature. Here,the output of MEMS device 36 is employed as the reference input signal(i.e., the reference clock). The PLL, DLL, digital/frequency synthesizerand/or FLL may provide frequency multiplication (i.e., increase thefrequency of the output signal of the MEMS oscillator). The PLL, DLL,digital/frequency synthesizer and/or FLL may also provide frequencydivision (i.e., decrease the frequency of the output signal of the MEMSoscillator). Moreover, the PLL, DLL, digital/frequency synthesizerand/or FLL may also compensate using multiplication and/or division toadjust, correct, compensate and/or control the characteristics (forexample, the frequency, phase and/or jitter) of the output signal of theMEMS resonator/oscillator.

With reference to FIG. 14H, thermistor 10 (in accordance with anyaspects and/or embodiments of the present inventions) may be integratedMEMS device 36 and integrated circuitry 42 on die 34. In thisembodiment, die 34 may include, in addition to thermistor 10, a MEMSresonator/oscillator (MEMS device 36) and data processing and clockgeneration circuitry to provide an integrated temperature compensatedMEMS oscillator. (See, for example, U.S. Pat. No. 6,995,622).

The multiplication or division (and/or phase adjustments) by the clockgeneration circuitry may be in fine or coarse increments. For example,the clock generation circuitry may include an integer PLL, a fractionalPLL and/or a fine-fractional-N PLL to precisely select, control and/orset the output signal of the MEMS resonator/oscillator. In this regard,the output of MEMS device 36 may be provided to the input of thefractional-N PLL and/or the fine-fractional-N PLL (hereinaftercollectively “fractional-N PLL”), which may be pre-set, pre-programmedand/or programmable to provide an output signal having a desired,selected and/or predetermined frequency and/or phase. Again, the dataprocessing circuitry may employ the data which is representative of thetemperature of the micromachined thermistor structure to adjust theparameters or values applied to such circuitry based on a measuredoperating temperature and/or changes in the operating temperature.

In other embodiment, the thermistor die (the die in/on which thermistor10 is fabricated) is physically coupled and stacked with other die, forexample, die having integrated circuitry 42 and MEMS device 36. (See,for example, FIGS. 14I-14N). In certain embodiments, thermistor die 34 ais stacked with integrated circuitry 42, and in other embodiments, die34 a, which includes thermistor 10 and MEMS device 36, is stacked withintegrated circuitry 42. As noted above, thermistor 10 may include oneor more micromachined thermistor structures 12 wherein, in thoseembodiments, where thermistor 10 includes more than one thermistorstructure, circuitry may receive a plurality of temperature data samplescorresponding to a plurality of different spatial regions in/on die 34and calculate and/or determine temperature related data (for example,the gradient in/on die 34, hot spots in/on die 34 and/or an averagetemperature across/in portions of die 34). In response, the circuitrymay control or adjust the control of circuitry (which employs the outputof the MEMS device 36). All combinations and/or permutations ofstacking, integration and/or number of thermistor structures areintended to fall within the scope of the present inventions.

Notably, in a stacked die configuration/architecture, it may beadvantageous to minimize any temperature gradient between the thermistorand the MEMS device. That gradient may be due to, for example, thermaltransfer from the integrated circuit die to the MEMS device die. Forexample, in one embodiment, the MEMS device die includes a MEMSresonator/oscillator to generate an output that is employed by clockgeneration circuitry to generate an clock output signal (see, forexample, FIGS. 1E and 1F), wherein changes in temperature of the MEMSresonator due the operation of circuitry on the integrated circuit diemay impact the frequency of the output of the MEMS resonator. As such,in one embodiment, with reference to FIG. 14M, die 34 a includes (i) athickness which is greater than the thickness of a standard die and/or(ii) a thermal insulating material (for example, a silicon nitride orsilicon oxide) disposed between die 34 a and die 34 b. In this way, thetemperature gradient between the thermistor and the MEMS device isreduced or minimized and the temperature dependent output signal ofthermistor 10 is more representative of the temperature of the MEMSstructure of MEMS device 36.

With reference to FIG. 14N, the stacked die architectures may include athermistor having a plurality of micromachined thermistor structures (inaccordance with aspects and/or embodiments of the present inventions).Here, a plurality of micromachined thermistor structures 12 arefabricated, manufactured or integrated on die 34 a with a MEMS device,wherein data from the thermistors may provide, for example, informationwhich is representative of (i) a temperature gradient in/on die 34 a,(ii) hot spots in/on the die, and/or (iii) an average temperatureacross/in portions of die 34 a. A die including a plurality ofmicromachined thermistor structures 12 may be implemented in any of thestacked die configurations, including, for example, the configuration ofFIG. 14M.

As intimated above, where the thermistor is disposed in a die which isdifferent from the die of the MEMS device and/or the die of theintegrated circuitry, the dice may be configured in a stacked diearchitecture (See, for example, FIGS. 14J-14L and 14O. In this regard,the thermistor (in accordance with aspects and/or embodiments of thepresent inventions) may be fabricated, manufactured or integrated on adie which is stacked with (i) a die having a MEMS device and/or (ii) adie having integrated circuitry. The dice may be stacked on each otheror in a side-by-side configuration. For example, where each of thethermistor, MEMS device and integrated circuitry fabricated,manufactured or disposed on a different die, the dice may be stacked oneach other (see, for example, FIG. 14L) or in a side-by-sideconfiguration (see, for example, FIG. 14O).

With reference to FIGS. 14Q and 14R, in one embodiment of the stackeddie architecture, a thermal coupler is employed to facilitate thermaltransfer/equilibrium between the dice of the thermistor and the MEMSdevice. In one embodiment the thermal coupler provides a low resistancethermal path or connection between the thermistor and the MEMS device.In this way, the output of the thermistor is more representative of ormore closely correlates to the temperature of the MEMS device.

In one embodiment, the thermal coupler is a thermal and/or electricalconductive epoxy wherein an “island” of such epoxy on or above theintegrated circuit die may encompass the dice of the thermistor and theMEMS device as well as secure or fix each die to the integrated circuitdie. In another embodiment, the thermal coupler is a metal trace or bar(which may be disposed on or suspended above the integrated circuit die.Again, the thermal coupler may be any material which provides a lowresistance thermal path or connection between the thermistor and theMEMS device so that the output of the thermistor is more representativeof or more closely correlates to the temperature of the MEMS device.

In another embodiment, the stacked die configuration may employ athermal coupler to provide a low resistance thermal path or connectionbetween the thermistor and the MEMS device and thermal isolator tothermally isolate and/or reduce thermal transfer of heat to/from theintegrated circuitry die from/to the MEMS device die and/or thethermistor die. With reference to FIG. 14S and 14T, in one embodiment,die 34 a of thermistor 10 and die 34 b of MEMS device 36 are arranged inside-by-side arrangement and fixed or secured on a thermal coupler. Thethermal coupler is fixed or secured (directly or indirectly) to athermal isolator which is fixed or secured (directly or indirectly) todie 34 c of integrated circuitry 42. In this way, the thermal couplerenhances the correlation between the output of the thermistor and thetemperature of the MEMS device. The thermal isolator reduces thermaltransfer to/from integrated circuitry die 34 c from/to MEMS device die34 b and/or thermistor die 34 a.

In one embodiment, the thermal isolator is a thermally isolatingmaterial, for example, a polyimide film. The thermal coupler may be ametal (for example, a metal film) such as copper or aluminum. Thethermal coupler may be a thermally conductive adhesive, as describedabove. Where the thermal coupler is electrically conductive, it may beadvantageous that the thermally isolating material also be electricallyisolating to enhance the reliability of the stacked die configuration.

With reference to FIG. 14U, in another embodiment, the dice of thethermistor and MEMS device are fixed or secured (directly or indirectly)to the thermal isolator via an adhesive-thermal coupler (for example, athermally and/or electrically conductive epoxy). Such a configurationeliminates the separate thermal coupler and, instead combines theadhesive and coupler.

Notably, the present inventions may employ a plurality of alternatingthermal isolators and conductors in a stacked configuration (forexample, an integrated circuitrydie—isolator—conductor—isolator—conductor . . . thermistor fixed orsecured to a thermal conductor (via, for example, an adhesive such as athermal epoxy)). This embodiment may enhance or improve the thermalisolation between (i) the integrated circuit die and (ii) the thermistordie (and MEMS die—if applicable) and/or thermal coupling between thethermistor die and MEMS die (where a MEMS device is included). Moreover,a plurality (for example, two or three) thermal isolator layers andthermal coupling layers may provide improved thermal isolation and/orthermal coupling relative to a thermal isolator and thermal couplerhaving substantially equal thickness to the plurality isolator layersand/or coupling layers, respectively.

The die having one or more thermistors according to any of theembodiments described and/or illustrated herein, whether stacked or not,may be packaged using any technique, configuration and/or packagingstructure now known or later developed. (See, for example, thetechniques and/or structure of U.S. Patent Application Publication2007/0290364 (including the provisional application upon which theaforementioned non-provisional application is based)). For example, inone embodiment, the die on which thermistor resides in or on (whether ornot the thermistor is integrated with other structures and/or integratedcircuitry) may be coupled to a lead frame (chip-on-lead (COL),chip-on-paddle (COP), and chip-on-tape (COT) packages) and thereafterencapsulated in a mold compound. In another embodiment, the thermistordie (whether or not the thermistor die includes other structures (forexample, MEMS device) and/or integrated circuitry) may be coupled toanother die in a stacked configuration and the combination coupled to alead frame (for example, COL, COP, COT packages) and thereafterencapsulated in a mold compound.

Notably, the die may be interconnected using any technique now known orlater developed including bond wires and/or balls (for example, in aflip-chip configuration), and/or a through-silicon viaarchitecture—thereby providing vertical connections through the body ofthe die.

In yet another embodiment, the thermistor die (or stacked diearchitecture) may be disposed, configured and/or provided in a surfacemount “package.” Such thermistor die may include other structures (forexample, MEMS device) and/or integrated circuitry. Again, the die havingone or more thermistors according to any of the embodiments describedand/or illustrated herein, whether stacked or not, may be packaged usingany technique, configuration and/or packaging structure now known orlater developed.

As mentioned above, the thermistor of the present inventions mayelectrically couple to measurement circuitry. (See, for example, FIGS.1B-1F). For example, in one embodiment, the measurement circuitryincludes resistance, voltage and/or current sensors (for example, an ohmmeter, a voltmeter and/or a current meter). Any resistance, voltageand/or current sensors, whether now known or later developed, may beemployed in conjunction with the thermistors of the present inventions.Indeed, the measurement circuitry may be configured in a 2-pointconfiguration/architecture (for example, ohm meter type circuitrycoupled to electrical connection or contact points of the thermistor) ora 3-point or 4-point configuration/architecture (for example, currentmeter and voltmeter type circuitry coupled to electrical connection orcontact points of the thermistor). Importantly, in one aspect, thepresent inventions are directed to measurement circuitry and methods ofoperating such circuitry. In one embodiment of this aspect of theinventions, the measurement circuitry provides low noise temperaturesensing with high accuracy, low power, and/or low area using athermistor element as the micromachined temperature sensitive device(for example, one or more of the thermistors of the present inventionswherein the resistance of the micromachined thermistor structure dependson or changes with temperature). For example, in one embodiment, themeasurement circuitry includes a switched capacitor network that createsa low noise adaptable reference resistor for comparison purposes, afrequency divider that is controlled by a digital Sigma-Delta modulatorto achieve an accurately controlled switching frequency for the switchedcapacitor network, a chopping method to mitigate the effect of 1/f noiseand circuit offsets, a pseudo-differential VCO-based analog-to-digitalconverter structure to efficiently convert the analog error between theMEMS-based resistance value and the effective resistance of the switchedcapacitor network into a digital code, and an overall feedback loop thatchanges a Sigma-Delta modulator input in response to that error. In thisway, the measurement circuitry minimizes the impact of non-idealities ofthe measurement system and/or configuration to measure the temperaturedependent characteristics of the micromachined thermistor structureand/or change therein (for example, resistance introduced via themeasurement circuitry) by measuring a parameter (for example,capacitance) that is a measure of but different from the temperaturedependent characteristics of the micromachined thermistor structure (forexample, resistance).

The measurement circuitry and methods of operating such circuitryaccording to this aspect of the present inventions is described andillustrated in detail in ATTACHMENT A to the Provisional Application.

With reference to FIG. 17A, in one embodiment, a thermal coupler 46interconnects thermistor 10 and MEMS device 36. The thermal coupler 46provides a low resistance thermal path or connection between thethermistor 10 and the MEMS device 36. In this way, thermistor 10 outputsdata which is more representative of the operating temperature of theMEMS structure of MEMS device 36. The thermal coupler 46 may be anymaterial now known or later developed that provides a low resistancethermal path. In one embodiment, thermal coupler 46 may be asemiconductor or metal material—for example, the same material used tofabricate the MEMS structure of MEMS device 36 and/or micromachinedthermistor structure 12 of thermistor 10. Moreover, the thermal couplermay be disposed laterally relative to the MEMS and thermistor structures(in a coplanar configuration) and/or vertically disposed relative to theMEMS and thermistor structures (in a stacked configuration). (See, FIGS.17B-17D and FIGS. 17E-17F, respectively). For example, in oneembodiment, the thermal coupler(s) interconnect anchors of the MEMS andthermistor structures. Indeed, in one embodiment, the MEMS andthermistor structures share one or more anchors which provide a lowresistance thermal path or connection between thermistor 10 and MEMSdevice 36. (See, FIG. 18). Notably, die 34 may include one or morethermistor structures, one or more MEMS structures, and a plurality ofthermal couplers 46 to provide low resistance thermal paths orconnections between thermistor 10 and MEMS device 36. In one embodiment,one or more micromachined thermistor structures 12 may be integrated orembedded in the MEMS device and coupled to the MEMS structure via one ormore thermal couplers 46. (See, for example, FIG. 17H).

As mentioned above, in addition to or in lieu of a thermistor includingone or more micromachined thermistor structures which are fabricatedfrom a temperature-sensitive crystalline material (for example, doped orundoped semiconductor material(s) such as, for example, monocrystalline,polycrystalline and/or amorphous silicon, germanium, silicon/germanium,silicon carbide (SiC), and gallium arsenide), the thermistor may includeone or more micromachined thermistor structure which are fabricated froma metal material (for example, platinum, aluminum, molybdenum and/orcopper (or alloys thereof)). (See, FIGS. 19A and 19B). The features,embodiments and/or inventions discussed and/or illustrated herein arefully applicable to thermistor 10 having one or more micromachinedthermistor structure which are fabricated from a metal material. For thesake of brevity, such discussions will not be repeated.

There are many inventions described and illustrated herein. Whilecertain embodiments, features, attributes and advantages of theinventions have been described and illustrated, it should be understoodthat many others, as well as different and/or similar embodiments,features, attributes and advantages of the present inventions, areapparent from the description and illustrations. As such, theembodiments, features, attributes and advantages of the inventionsdescribed and illustrated herein are not exhaustive and it should beunderstood that such other, similar, as well as different, embodiments,features, attributes and advantages of the present inventions are withinthe scope of the present inventions.

Indeed, the present inventions are neither limited to any single aspectnor embodiment thereof, nor to any combinations and/or permutations ofsuch aspects and/or embodiments. Moreover, each of the aspects of thepresent inventions, and/or embodiments thereof, may be employed alone orin combination with one or more of the other aspects of the presentinventions and/or embodiments thereof.

For example, micromachined thermistor structure 12 may include any shapenow known or later developed. In one embodiment, the thermistorstructure 12 includes “rounded” corners to reduce stress points/regionsof the structure. (See, for example, FIGS. 20A-20D, 21A-21F, 23A-23D,24A and 24B). In addition, “sharp” corners in the current path of thestructure may present increased concentrations of electrical currentdensity in the micromachined thermistor structure. As such, structureshaving “rounded” corners may reduce the potential of increased currentconcentrations within the micromachined thermistor structure.

In addition, to facilitate signal/current flow in micromachinedthermistor structure 12, it may be advantageous to locate anchors (orportions/areas under stress) remote from the signal flow (for example,current flow) through or in the micromachined thermistor structure.(See, for example, anchor 16 in the exemplary micromachined thermistorstructure embodiments illustrated in FIGS. 20A-20D, 21A-21F, 23A-23D,24A and 24B). In this way, thermistor 10 may provide a more accurateand/or a more reliable representation of the ambient temperatureregardless of the non-temperature related/dependent ambient operatingconditions of the thermistor (for example, substrate stress or forces(internal or external) applied thereto). A detailed technical discussionof certain aspects of the deformation of a silicon resistor structuredue to stress (from the package or otherwise) is provided in ATTACHMENTB to the Provisional Application.

Where thermistor 10 is encapsulated, for example, via a MEMSfabrication, encapsulation and packaging process as described andillustrated in U.S. Pat. No. 6,936,491 and/or U.S. Pat. No. 7,075,160,vents are formed in an encapsulation layer to etch or remove asacrificial layer thereby substantially or entirely releasing(vertically and horizontally) micromachined thermistor structure. Withreference to FIGS. 21A-21F, 23A-23D, vents 44 may be located (i)directly over portions of micromachined thermistor structure 12 (see,for example, FIGS. 21A, 21B and 21D), or (ii) remote from portions ofmicromachined thermistor structure 12 (see, for example, FIG. 21C), or(iii) adjacent to portions of structure 12 (see, for example, FIGS. 21Eand 21F).

Briefly, with reference to FIGS. 22A-22F, in one exemplary embodiment,as discussed above, after defining micromachined thermistor structure 12(see FIG. 22A), a process of fabricating a thin-film encapsulationstructure starts with depositing or providing sacrificial layer 24 overmicromachined thermistor structure 12. (See FIG. 22B). Thereafter, layer26 is provided, for example, formed, deposited and/or grown. (See FIG.22C). Vents 44 are then formed in encapsulation layer 26. (See FIG.22D). Notably, in the illustrated embodiment, vents 44 are formed inencapsulation layer 26 directly over portions of micromachinedthermistor structure 12 (see, for example, FIG. 21A). Thereafter,sacrificial layer 24 is removed or etched around micromachinedthermistor structure 12 thereby substantially or entirely releasing(vertically and horizontally) micromachined thermistor structure 12.(See, FIG. 22E).

After releasing micromachined thermistor structure 12, in oneembodiment, vents 44 may be closed and cavity 50 is sealed viadeposition of layer 28. (See, FIG. 22F). Notably, material correspondingto layer 28 may collect in vents 44 (as illustrated in FIG. 22F), entercavity 50, and/or deposit on micromachined thermistor structure 12. Assuch, it may be advantageous to locate vents 44 (ii) remote fromportions of micromachined thermistor structure 12. (See, for example,FIG. 21C).

As mentioned above, MEMS device 36 may include one or more MEMSstructures and may be any shape or device now known or later developed.For example, the MEMS device may include one or more structures toprovide a gyroscope, resonator, pressure sensor and/or accelerometer,made in accordance with well-known fabrication techniques, such aslithographic and other precision fabrication techniques, which formmechanical components to a scale that is generally comparable tomicroelectronics.

In certain embodiments, the micromachined thermistor structures includeone or more loop-shape portions. The radii of the loop-shape portionsmay differ and be designed and fabricated to facilitate a more uniformcurrent flow throughout the micromachined thermistor structure and inparticular, through the loop-shape portion of the micromachinedthermistor structure. (Compare FIGS. 25A, 25B and 25C). Notably, theloop-shape portion of the micromachined thermistor structures mayinclude portions that are not curved but the combination, as a whole, isloop-shaped. For example, with reference to FIG. 25C, the loop-shapedportion may include one or more straight portions between or separatingtwo curved end portions wherein the combination, as a whole, isloop-shaped.

Notably, although, at times, the present inventions have been describedand/or illustrated in relation to or in the context of asemiconductor-on-insulator (SOI) substrate. For example, thesemiconductor layer of the SOI substrate may be materials in column IVof the periodic table, for example, silicon, germanium, carbon; alsocombinations of these, for example, silicon germanium, or siliconcarbide; also of III-V compounds, for example, gallium phosphide,aluminum gallium phosphide, or other III-V combinations; alsocombinations of III, IV, V, or VI materials, for example, siliconnitride, silicon oxide, aluminum carbide, or aluminum oxide; alsometallic silicides, germanides, and carbides, for example, nickelsilicide, cobalt silicide, tungsten carbide, or platinum germaniumsilicide; also doped variations including phosphorus, arsenic, antimony,boron, or aluminum doped silicon or germanium, carbon, or combinationslike silicon-germanium; also these materials with various crystalstructures, including single/mono crystalline, polycrystalline,nanocrystalline, or amorphous; also with combinations of crystalstructures, for instance with regions of single crystalline andpolycrystalline structure (whether doped or undoped). Notably, themechanical and/or thermistor structures may be comprised of the samematerials as described above with respect to the first semiconductorlayer.

Other substrates are also suitable—including, an insulating material(for example, a ceramic material, a glass material, a silicon oxidematerial and a silicon nitride material). The substrate may be asemiconductor material of a standard wafer (for example, amonocrystalline or polycrystalline silicon wafer) having an insulator orsacrificial layer deposited thereon. Moreover, the substrate may be ametal material. All substrates now known or later developed are intendedto fall within the scope of the present inventions.

It should be further noted that various structures (for example, thestructures of the thermistor and/or MEMS device), circuits and/orcircuitry (for example, the measurement circuitry (including thematerial in ATTACHMENT A to the Provisional Application), dataprocessing circuitry and clock generation circuitry) disclosed hereinmay be described using computer aided design tools and expressed (orrepresented), as data and/or instructions embodied in variouscomputer-readable media, in terms of their behavioral, registertransfer, logic component, transistor, layout geometries, and/or othercharacteristics. Formats of files and other objects in which suchstructure and/or circuit expressions may be implemented include, but arenot limited to, formats supporting behavioral languages such as C,Verilog, and HDL, formats supporting register level descriptionlanguages like RTL, and formats supporting geometry descriptionlanguages such as GDSII, GDSIII, GDSIV, CIF, MEBES and any othersuitable formats and languages. Computer-readable media in which suchformatted data and/or instructions may be embodied include, but are notlimited to, non-volatile storage media in various forms (e.g., optical,magnetic or semiconductor storage media) and carrier waves that may beused to transfer such formatted data and/or instructions throughwireless, optical, or wired signaling media or any combination thereof.Examples of transfers of such formatted data and/or instructions bycarrier waves include, but are not limited to, transfers (uploads,downloads, e-mail, etc.) over the Internet and/or other computernetworks via one or more data transfer protocols (e.g., HTTP, FTP, SMTP,etc.).

Indeed, when received within a computer system via one or morecomputer-readable media, such data and/or instruction-based expressionsof the above described structures, circuits and/or circuitry may beprocessed by a processing entity (e.g., one or more processors) withinthe computer system in conjunction with execution of one or more othercomputer programs including, without limitation, net-list generationprograms, place and route programs and the like, to generate arepresentation or image of a physical manifestation of such structures,circuits and/or circuitry. Such representation or image may thereafterbe used in device fabrication, for example, by enabling generation ofone or more masks that are used to form various components of thecircuits in a device fabrication process.

Moreover, the various structures various structures (for example, thestructures of the thermistor and/or MEMS device), circuits and/orcircuitry (for example, the measurement circuitry (including thecircuitry of material in ATTACHMENT A to the Provisional Application),data processing circuitry and clock generation circuitry) disclosedherein may be represented via simulations using computer aided designand/or testing tools. The simulation of the various structures (forexample, the structures of the thermistor and/or MEMS device), circuitsand/or circuitry (for example, the measurement circuitry (including thecircuitry of the material in ATTACHMENT A to the ProvisionalApplication), data processing circuitry and clock generation circuitry),and/or characteristics or operations thereof, may be implemented by acomputer system wherein characteristics and operations of suchstructures and/or circuitry, and techniques implemented thereby, areimitated, replicated and/or predicted via a computer system. The presentinventions are also directed to such simulations of the inventivestructures and circuitry, and/or techniques implemented thereby, and, assuch, are intended to fall within the scope of the present inventions.The computer-readable media corresponding to such simulations and/ortesting tools are also intended to fall within the scope of the presentinventions.

It should be noted that the term “circuit” may include, among otherthings, a single component (for example, electrical/electronic and/ormicroelectromechanical) or a multiplicity of components (whether inintegrated circuit form, discrete form or otherwise), which are activeand/or passive, and which are coupled together to provide or perform adesired function. The term “circuitry” may include, among other things,a circuit (whether integrated or otherwise), a group of such circuits,one or more processors, one or more state machines, one or moreprocessors implementing software, one or more gate arrays, programmablegate arrays and/or field programmable gate arrays, or a combination ofone or more circuits (whether integrated, discrete or otherwise), one ormore state machines, one or more processors, one or more processorsimplementing software, one or more gate arrays, programmable gate arraysand/or field programmable gate arrays. The term “data” may mean, amongother things, a current or voltage signal(s) whether in an analog or adigital form.

Notably, the terms “first,” “second,” and the like, herein do not denoteany order, quantity, or importance, but rather are used to distinguishone element from another. Moreover, in the claims, the terms “a” and“an” herein do not denote a limitation of quantity, but rather denotethe presence of at least one of the referenced item.

What is claimed is:
 1. A microelectromechanical system (MEMS) devicecomprising: a substrate; a microelectromechanical resonator secured tothe substrate at a first location; a micromachined thermistor havingfirst and second ends secured to the substrate at respective second andthird locations, and having a length from the first end to the secondend greater than a linear distance between the second and thirdlocations, the micromachined thermistor being thermally coupled to themicroelectromechanical resonator to enable a temperature-dependentresistance of the micromachined thermistor to vary according to atime-varying temperature of the microelectromechanical resonator; andcircuitry electrically coupled to the micromachined thermistor andelectrically coupled to the microelectromechanical resonator.
 2. TheMEMS device of claim 1 wherein the micromachined thermistor is thermallycoupled to the microelectromechanical resonator via one or more thermalcoupling structures that are distinct from the substrate.
 3. The MEMSdevice of claim 1 wherein the circuitry is disposed on a substrate thatis distinct from the substrate to which the microelectromechanicalresonator and micromachined thermistor are secured.
 4. The MEMS deviceof claim 1 wherein the circuitry generates temperature informationbased, at least in part, on the temperature-dependent resistance of themicromachined thermistor and generates a clock signal having atemperature-compensated frequency based on mechanical motion of themicroelectromechanical resonator and based on the temperatureinformation.
 5. The MEMS device of claim 1 wherein the circuitry isthermally isolated from the micromachined thermistor.
 6. The MEMS deviceof claim 1 further comprising first and second anchor structuresdisposed at the second and third locations, respectively, and physicallycoupled to the first and second ends of the micromachined thermistor tosecure the micromachined thermistor to the substrate.
 7. The MEMS deviceof claim 6 wherein the micromachined thermistor is thermally coupled tothe microelectromechanical resonator, at least in part, via the at leastone of the first and second anchor structures.
 8. The MEMS device ofclaim 1 wherein the circuitry comprises: measurement circuitry togenerate temperature information based at least in part on thetemperature-dependent resistance of the micromachined thermistor; andoutput circuitry to generate an output signal in accordance with asignal indicative of mechanical motion of the microelectromechanicalresonator and dependent, at least in part, on the temperatureinformation.
 9. The MEMS device of claim 8 wherein the output circuitryto generate the output signal in accordance with the signal indicativeof mechanical motion of the microelectromechanical resonator anddependent, at least in part, on the temperature information comprisescircuitry to generate a clock signal in accordance with the signalindicative of mechanical motion of the microelectromechanical resonatorand to adjust the frequency of the clock signal based on the temperatureinformation.
 10. The MEMS device of claim 8 wherein the output circuitryto generate the output signal in accordance with the signal indicativeof mechanical motion of the microelectromechanical resonator anddependent, at least in part, on the temperature information comprisescircuitry to generate a clock signal in accordance with the signalindicative of the mechanical motion of the microelectromechanicalresonator and to control the mechanical motion of themicroelectromechanical resonator based, at least in part, on thetemperature information.
 11. A non-transitory machine-readable mediumthat stores data representative of a microelectromechanical system(MEMS) device comprising: a microelectromechanical resonator secured toa substrate at a first location; a micromachined thermistor having firstand second ends secured to the substrate at respective second and thirdlocations, and having a length from the first end to the second endgreater than a linear distance between the first and second locations,the micromachined thermistor being thermally coupled to themicroelectromechanical resonator to enable a temperature-dependentresistance of the micromachined thermistor to vary according to atime-varying temperature of the microelectromechanical resonator; andcircuitry electrically coupled to and thermally isolated from themicromachined thermistor and electrically coupled to themicroelectromechanical resonator.
 12. A method of fabricating amicroelectromechanical system (MEMS) device, the method comprising:forming, with respect to a first substrate of the MEMS device, amicroelectromechanical resonator that is secured to the substrate at afirst location, and a micromachined thermistor having first and secondends secured to the substrate at respective second and third locations,the micromachined thermistor having a length from the first end to thesecond end greater than a linear distance between the second and thirdlocations, and being thermally coupled to the microelectromechanicalresonator to enable a temperature-dependent resistance of themicromachined thermistor to vary according to a time-varying temperatureof the microelectromechanical resonator; and implementing circuitrywithin the MEMS device that is electrically coupled to both themicromachined thermistor and the microelectromechanical resonator. 13.The method of claim 12 wherein forming the micromachined thermistor thatis thermally coupled to the microelectromechanical resonator comprisesthermally coupling the micromachined thermistor to themicroelectromechanical resonator via one or more thermal couplingstructures that are distinct from the substrate.
 14. The method of claim12 wherein implementing the circuitry within the MEMS device that iselectrically coupled to both the micromachined thermistor and themicroelectromechanical resonator comprises forming the circuitry on asubstrate that is distinct from the first substrate.
 15. The method ofclaim 12 wherein implementing the circuitry comprises implementingcircuitry that generates temperature information based, at least inpart, on the temperature-dependent resistance of the micromachinedthermistor and generates a clock signal having a temperature-compensatedfrequency based at least in part on (i) mechanical motion of themicroelectromechanical resonator and (ii) the temperature information.16. The method of claim 12 wherein implementing the circuitryelectrically coupled to both the micromachined thermistor and themicroelectromechanical resonator comprises thermally isolating thecircuitry from the micromachined thermistor.
 17. The method of claim 12wherein forming the micromachined thermistor having first and secondends secured to the substrate at respective second and third locationscomprises securing the first and second ends of the micromachinedthermistor to the substrate via respective first and second anchorstructures disposed at the second and third locations.
 18. The method ofclaim 17 wherein the micromachined thermistor is thermally coupled tothe microelectromechanical resonator, at least in part, via the at leastone of the first and second anchor structures.
 19. The method of claim12 wherein implementing the circuitry comprises implementing (i)measurement circuitry to generate temperature information based at leastin part on the temperature-dependent resistance of the micromachinedthermistor, and (ii) output circuitry to generate an output signal inaccordance with a signal indicative of mechanical motion of themicroelectromechanical resonator and dependent, at least in part, on thetemperature information.
 20. The method of claim 19 wherein implementingthe output circuitry to generate the output signal in accordance withthe signal indicative of mechanical motion of the microelectromechanicalresonator and dependent, at least in part, on the temperatureinformation comprises implementing circuitry to generate a clock signalin accordance with the signal indicative of mechanical motion of themicroelectromechanical resonator and to adjust the frequency of theclock signal based on the temperature information.
 21. The method ofclaim 19 wherein the implementing the output circuitry to generate theoutput signal in accordance with the signal indicative of mechanicalmotion of the microelectromechanical resonator and dependent, at leastin part, on the temperature information comprises implementing circuitryto generate a clock signal in accordance with the signal indicative ofthe mechanical motion of the microelectromechanical resonator and tocontrol the mechanical motion of the microelectromechanical resonatorbased, at least in part, on the temperature information.